HQRP Drive and Worm Gear Kit for Craftsman 13953985D 13953985DM 1395399011 13953990D 13953990DS 13953990SRT 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!