✨[Product Overview] This is a T-Rail Trolley Replacement Kit. 41A3489 Garage Door Opener Carriage, Complete Trolley Assembly Chain Drive ✨[Compatibility] For use with various Liftmaster, Chamberlain, Sears Craftsman Garage Door Openers that utilize a T-rail assembly. Not Compatible with square box rail ✨[Product Function] This trolley is the perfect solution for your belt drive garage door opener repair and maintenance needs ✨[Premium Quality] T-Rail Trolley Replacement Kit Crafted from high-quality materials, ensures smooth and reliable operation ✨[Package Includes] One Trolley, Master Link Clip-On Spring (2 pcs), Master Link Cap (2 pcs), Master Link Bar (2 pcs), Trolley Shaft, One Section Heavy-duty Chain Drive, Connecting Hardware, Garage Door Emergency Release Pull Cord ✨[Note] Not Compatible with square box rail, Check the manual or replacement parts diagram for specific part information before ordering to ensure compatibility 41A3489 Garage Door Opener Carriage, Complete T-Rail Trolley Assembly, Compatible with Most Popular Brands, Chain Drive Operators Made by Liftmaster, Chamberlain, Sears Craftsman