For 10' Garage Doors. Garage Door Rail Extension Kits | Chamberlain GARAGE DOOR RAIL EXTENSION KITS Use genuine Chamberlain rail extension kits if you need to add additional railing to your garage door tracks. Dimensions: 3.06" x 2.06" x 50.31" Featuring a quick-install extension rail and replacement chain, the kit includes everything needed for quick and easy installation. This belt drive rail extension kit features a quick-install rail system. Heavy Duty Chain Drive Rail Extension Kit The Heavy Duty Chain Extension Kit for 8 The Heavy Duty Chain Extension Kit for 8 ft. High Garage Doors is required for reliable, everyday operation of Chamberlain heavy duty chain drive models in 8 ft. garage door applications. Featuring a quick-install extension rail and replacement chain, the kit includes everything needed for quick and easy installation. Product Overview. Kits can extend rails to 8' or 10'. Description & Documents This Chamberlain® Extension Kit is needed for garage doors that are 10 feet high and are compatible with Chamberlain® belt drive garage door openers. The Chain Drive Rail Extension Kit for 8 ft. High Garage Doors is required for reliable, everyday operation of Chamberlain chain drive models in 8 ft. garage door applications. The belt drive rail extension kit for 8-ft high garage doors is required for reliable, everyday operation of Chamberlain® belt drive models in … The Chamberlain-8 ft Belt-Drive Extension Kit is compatible with Chamberlain Whisper Drive and Whisper Drive plus belt-drive garage door openers. Chamberlain 8 ft. Required for reliable, everyday operation of Rails. Chamberlain 7708CB-P Chain Drive Rail Extension Kit for 8 Foot High Garage Doors