The Steele Rubber Products 1" Bulb Seal features a rigid "C" channel section that slides onto the track located on the wiper seal. Its main function is to seal against the RV when the slide-out is closed, protecting your RV from extreme weather and pests. Unique fins help prevent side-flop when compressed and increase the contact surface size at the same time. This bulb seal is an excellent upgrade to existing weatherstripping for a more complete seal. It can also be used to upgrade just the top seal of a slide-out to add even better weatherproofing. Seen on many new trailers. 1"H x 1"W (1-1/2"W at fins) x 15'L. Protects RV from extreme weather & pests Unique fins increase the contact surface size & help prevent side-flop Measures 1""H x 1""W (1.5""W at fins) x 15'L | Steele Rubber Products 1" Bulb Seal with Fins, 15' long