HQRP Drive and Worm Gear Kit for Craftsman 13953614SR 139536151SR 13953615SR 139536181SR 13953618SR 139536191SR Garage Door Opener Access System + HQRP Coaster HQRP&reg; Replacement Drive Gear and Worm Gear Kit plus HQRP&reg; Coaster; It Is Highly Recommended That You Replace Both The Drive Gear And Worm Gear At The Same Time; 100 Days Warranty!