The most common cause for a replacement spring not fitting properly is that the spring and shade may be from different manufacturers, which leads to slight dimensional differences. To ensure the correct fit for your Slow Rise RV shade, first confirm the shade brand—if it is Irvine, you will need their specific replacement spring. These springs come in sizes extra small, small, medium, and large. To select the right size, measure the width of the roller tube itself (not just the fabric) from one end cap to the other. For Irvine 1.25" Slow Rise springs, use the following guide: 9–19" width requires extra small, 20–29" small, 30–59" medium, and 60" or wider large. If you already ordered the medium size for a 52" shade and it did not fit, double-check your measurements and the spring diagrams on the product page to verify compatibility. You can find the correct Irvine replacement springs on our website, selecting the size that matches your roller tube measurement for a proper fit.