This is a T-Rail Trolley Replacement Kit. For use with various LiftMaster and Chamberlain Garage Door Openers that utilize a T-rail assembly. Check the manual or replacement parts diagram for specific part information before ordering to ensure compatibility. Genuine LiftMaster replacement part. This is a T-Rail Trolley Replacement Kit - Also known as: 1B1435, 41B3215, 41B2617, 65411, 1A955, 41A3489, 4A1020, 062245, 1B3869, 4A1051, 41B2771 For use on must / various LiftMaster and Chamberlain Garage Door Openers that utilize a T-rail assembly Check the manual or replacement parts diagram for specific part information before ordering to ensure compatibility. Genuine LiftMaster replacement part. Item Weight 1 pounds Manufacturer Liftmaster Item model number 41A3489 / 041A3489 Product Dimensions 4 x 2 x 2 inches Included Components Trolley Kit