If the replacement springs you received do not fit properly due to diameter differences, you can return the incorrect parts for a full refund. To do this, log into your account on our website where you can request a return label and process the return easily. Regarding the aluminum tube, it’s recommended to order a size that matches the spring you already have to ensure proper torsion function. If you are unsure about the correct tube size, please contact us with your spring specifications, and we can assist in recommending the appropriate aluminum tube length. Returning the incorrect parts and placing a new order for the correct items will help avoid confusion and ensure you receive compatible components for your RV roller shades.