{"product_id":"cpi-3-inch-hub-adaptor-o-ring-3-75-hole-size-part-300","title":"CPI - 3\" Hub Adaptor with O Ring - 3.75\" Hole Size - Part # 300","description":"\u003cdiv style=\"background-color: #f3f4f6; border-left: 4px solid #1d9bf0; padding: 16px; margin-bottom: 16px;\"\u003e\n  \u003cp style=\"margin: 0; color: #1d9bf0; font-weight: bold;\"\u003e✓ ElkhartRVParts.com - The Only Authorized Place for CPI Parts\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cdiv style=\"background-color: #f3f4f6; border-left: 4px solid #10b981; padding: 16px; margin-bottom: 20px;\"\u003e\n  \u003cp style=\"margin: 0; color: #10b981; font-weight: bold;\"\u003e✓ 100% Verified Authentic OEM Grade Part\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cp\u003eThe \u003cstrong\u003eCPI 3\" Hub Adaptor with O Ring (Part # 300)\u003c\/strong\u003e is the professional-grade solution for creating secure, leak-free connections on RV holding tanks and fresh water systems. Designed for 3.75\" hole sizes, this hub adaptor features an integrated O-ring seal that ensures reliable performance in demanding mobile environments where vibration and temperature changes are constant challenges.\u003c\/p\u003e\n\n\u003ch2\u003eFeatures \u0026amp; Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrecision Fit:\u003c\/strong\u003e Engineered for 3.75\" (3 3\/4\") hole size with exact tolerances for proper sealing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntegrated O-Ring Seal:\u003c\/strong\u003e Pre-installed O-ring provides superior leak protection compared to gasket-only designs\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Grade Construction:\u003c\/strong\u003e Manufactured by CPI (Elkhart Plastics) to original equipment specifications\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDurable Materials:\u003c\/strong\u003e High-impact plastic construction resists cracking, UV damage, and chemical exposure\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLightweight Design:\u003c\/strong\u003e Only 0.8 lbs for easy handling during installation\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUniversal Compatibility:\u003c\/strong\u003e Works with standard 3\" plumbing connections on RV tanks\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number 300 (500288):\u003c\/strong\u003e Direct OEM replacement for factory-installed fittings\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhy Choose the CPI 3\" Hub Adaptor with O Ring?\u003c\/h2\u003e\n\u003cp\u003eWhen you're replacing or upgrading RV tank fittings, the quality of your hub adaptor directly impacts system reliability. The \u003cstrong\u003eCPI 3\" Hub Adaptor with O Ring\u003c\/strong\u003e eliminates common failure points found in inferior fittings. The integrated O-ring design creates a compression seal that maintains integrity even as your RV travels over rough roads. Unlike cheaper alternatives that rely solely on threaded connections, this hub adaptor's O-ring provides a secondary seal that prevents leaks before they start. CPI's reputation for manufacturing OEM-grade RV components means you're installing the same quality fitting that RV manufacturers trust in new production.\u003c\/p\u003e\n\n\u003ch2\u003eCompare 3\" RV Tank Fittings\u003c\/h2\u003e\n\u003cp\u003eChoosing the right tank fitting depends on your hole size, installation method, and sealing requirements. Here's how the CPI Hub Adaptor compares to other popular 3\" fittings:\u003c\/p\u003e\n\n\u003cdiv style=\"overflow-x: auto; margin: 20px 0;\"\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; border: 1px solid #e5e7eb;\"\u003e\n  \u003cthead\u003e\n    \u003ctr style=\"background-color: #dc2626; color: white;\"\u003e\n      \u003cth style=\"padding: 12px; text-align: left; border: 1px solid #e5e7eb;\"\u003eModel (Part #)\u003c\/th\u003e\n      \u003cth style=\"padding: 12px; text-align: left; border: 1px solid #e5e7eb;\"\u003eHole Size\u003c\/th\u003e\n      \u003cth style=\"padding: 12px; text-align: left; border: 1px solid #e5e7eb;\"\u003eSeal Type\u003c\/th\u003e\n      \u003cth style=\"padding: 12px; text-align: left; border: 1px solid #e5e7eb;\"\u003eMaterial\u003c\/th\u003e\n      \u003cth style=\"padding: 12px; text-align: left; border: 1px solid #e5e7eb;\"\u003eBest For\u003c\/th\u003e\n      \u003cth style=\"padding: 12px; text-align: left; border: 1px solid #e5e7eb;\"\u003eView Details\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr style=\"background-color: #fef2f2; border-left: 3px solid #dc2626;\"\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e\u003cstrong\u003eCPI Hub Adaptor (300)\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e3.75\"\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eIntegrated O-Ring\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eHigh-Impact Plastic\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eStandard tank connections requiring secure O-ring seal\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e\u003cem\u003eCurrent Product\u003c\/em\u003e\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e\u003cstrong\u003eCPI Flex Rubber (93)\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e3.875\"\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eFlexible Rubber Gasket\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eBlack Rubber\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eApplications needing flexibility and vibration dampening\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e\u003ca href=\"https:\/\/elkhartrvparts.com\/products\/cpi-3-flex-black-rubber-tank-fitting-3-7-8-hole-size-part-93-500125\" style=\"color: #dc2626; font-weight: bold;\"\u003eView Product\u003c\/a\u003e\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e\u003cstrong\u003eICON Threaded Flush (HW\/SLF-300)\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eVaries\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eThreaded Connection\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eABS Plastic\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eFlush-mount threaded applications\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e\u003ca href=\"https:\/\/elkhartrvparts.com\/products\/icon-fitting-threaded-3-inch-flush-hwslf-300\" style=\"color: #dc2626; font-weight: bold;\"\u003eView Product\u003c\/a\u003e\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e\u003cstrong\u003eICON Spigot (HW\/SLF-400)\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eVaries\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eSpigot Connection\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eABS Plastic\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003eSpigot-style drain connections\u003c\/td\u003e\n      \u003ctd style=\"padding: 12px; border: 1px solid #e5e7eb;\"\u003e\u003ca href=\"https:\/\/elkhartrvparts.com\/products\/icon-fitting-spigot-3-inch-hwslf-400\" style=\"color: #dc2626; font-weight: bold;\"\u003eView Product\u003c\/a\u003e\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003cp style=\"background-color: #f3f4f6; padding: 12px; border-left: 3px solid #dc2626; margin: 20px 0;\"\u003e\u003cstrong\u003ePro Tip:\u003c\/strong\u003e Always measure your existing hole size before ordering. The 3.75\" hole size is standard for many RV tanks, but verify your specific application to ensure proper fit.\u003c\/p\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e 300 (also known as 500288)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e CPI (Elkhart Plastics)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConnection Size:\u003c\/strong\u003e 3\" hub diameter\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRequired Hole Size:\u003c\/strong\u003e 3.75\" (3 3\/4\")\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOverall Dimensions:\u003c\/strong\u003e 3\" diameter hub\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.8 lbs\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e High-impact plastic with integrated O-ring seal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e Standard tank fitting color\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e RV holding tanks, fresh water tanks, gray water systems\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstallation:\u003c\/strong\u003e Requires 3.75\" hole saw for new installations\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Standard 3\" plumbing connections\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat's Included\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e1x CPI 3\" Hub Adaptor (Part # 300)\u003c\/li\u003e\n\u003cli\u003e1x Pre-installed O-Ring seal\u003c\/li\u003e\n\u003cli\u003eManufacturer's quality guarantee\u003c\/li\u003e\n\u003cli\u003eOEM-grade construction for reliable performance\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eCompatible Models \u0026amp; Alternatives\u003c\/h2\u003e\n\u003cp\u003eThis hub adaptor works with any RV tank requiring a 3.75\" hole fitting. If you need a different hole size, consider the \u003ca href=\"https:\/\/elkhartrvparts.com\/products\/cpi-3-flex-black-rubber-tank-fitting-3-7-8-hole-size-part-93-500125\" style=\"color: #dc2626; font-weight: bold;\"\u003eCPI 3\" Flex Black Rubber Tank Fitting (Part # 93)\u003c\/a\u003e for 3.875\" holes, or browse our complete \u003ca href=\"https:\/\/elkhartrvparts.com\/collections\/rv-tank-fittings\" style=\"color: #dc2626; font-weight: bold;\"\u003eRV Tank Fittings Collection\u003c\/a\u003e for other sizes and styles.\u003c\/p\u003e\n\n\u003cp\u003eNeed to replace just the O-ring? We also carry the \u003ca href=\"https:\/\/elkhartrvparts.com\/products\/o-ring-only-for-3-hub-adaptor-3-3-4-hole-size-part-300-oring\" style=\"color: #dc2626; font-weight: bold;\"\u003eO-Ring ONLY for 3\" Hub Adaptor (Part # 300-O'RING)\u003c\/a\u003e for maintenance and repairs.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\n\u003ch3\u003eHow do I install the CPI 3\" Hub Adaptor?\u003c\/h3\u003e\n\u003cp\u003eInstallation requires a 3.75\" hole in your tank wall. Insert the hub adaptor from the inside of the tank, ensuring the O-ring is properly seated. Secure from the outside using the appropriate threaded connection or clamp. Always test for leaks before putting the tank into service.\u003c\/p\u003e\n\n\u003ch3\u003eIs this compatible with my RV's holding tank?\u003c\/h3\u003e\n\u003cp\u003eThis hub adaptor fits any RV tank with a 3.75\" hole size and 3\" plumbing connections. It's a universal OEM-grade fitting used by many RV manufacturers. Measure your existing hole or check your tank specifications to confirm compatibility.\u003c\/p\u003e\n\n\u003ch3\u003eWhat's the difference between this and the rubber flex fitting?\u003c\/h3\u003e\n\u003cp\u003eThe hub adaptor (Part # 300) uses a rigid plastic construction with an integrated O-ring seal, ideal for standard installations. The flex rubber fitting (Part # 93) offers more flexibility and vibration dampening but requires a slightly larger 3.875\" hole. Choose based on your specific installation requirements.\u003c\/p\u003e\n\n\u003ch3\u003eCan I replace just the O-ring if it wears out?\u003c\/h3\u003e\n\u003cp\u003eYes, replacement O-rings are available separately as Part # 300-O'RING. Regular O-ring replacement during routine maintenance can extend the life of your hub adaptor and prevent leaks.\u003c\/p\u003e\n\n\u003ch3\u003eWhat tools do I need for installation?\u003c\/h3\u003e\n\u003cp\u003eFor new installations, you'll need a 3.75\" hole saw. For replacements, basic hand tools to remove the old fitting and install the new one. Always follow proper safety procedures when working with tank systems.\u003c\/p\u003e\n\n\u003ch3\u003eIs this fitting suitable for fresh water tanks?\u003c\/h3\u003e\n\u003cp\u003eYes, the CPI 3\" Hub Adaptor is suitable for fresh water, gray water, and black water holding tanks. The materials are safe for potable water applications and resistant to the chemicals used in RV sanitation systems.\u003c\/p\u003e\n\n\u003ch2\u003eWhy Buy from Elkhart RV Parts?\u003c\/h2\u003e\n\u003cp\u003eElkhart RV Parts is your trusted source for authentic OEM-grade RV components. We stock only verified genuine parts from authorized manufacturers like CPI (Elkhart Plastics). Every hub adaptor we sell meets or exceeds original equipment specifications. Our team understands RV systems and can help you find the right parts for your specific application. We offer fast shipping, secure packaging, and a satisfaction guarantee on all products.\u003c\/p\u003e\n\n\u003cdiv style=\"background-color: #fef2f2; border-left: 4px solid #dc2626; padding: 16px; margin-top: 20px;\"\u003e\n  \u003cp style=\"margin: 0; font-weight: bold; color: #dc2626;\"\u003eReady to Install a Reliable Tank Fitting?\u003c\/p\u003e\n  \u003cp style=\"margin: 8px 0 0 0;\"\u003eOrder your CPI 3\" Hub Adaptor today and enjoy secure, leak-free performance. Have questions? Our AI Live Chat is available to help you find the perfect fitting for your RV tank system.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"CPI","offers":[{"title":"Default Title","offer_id":32789634383931,"sku":"300","price":4.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0346\/2397\/9579\/files\/cpi-3-inch-hub-adaptor-o-ring-3-75-hole-size-part-300-shopify-1.jpg?v=1779179935","url":"https:\/\/elkhartrvparts.com\/en-ca\/products\/cpi-3-inch-hub-adaptor-o-ring-3-75-hole-size-part-300","provider":"Elkhart RV Parts","version":"1.0","type":"link"}