HQRP Drive and Worm Gear Kit for LiftMaster 41A2817 41C4220 41C4220A 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!