Chamberlain 7708CB-P Chain Drive Rail Extension Kit for 8 Foot High Garage Doors Product Description The Chain Drive Rail Extension Kit for 8'-High Garage Doors is required for reliable, everyday operation of Chamberlain 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.Includes one-year warranty, rail extension, replacement chain, all necessary hardware and an instruction manual for easy setup. From the Manufacturer Chamberlain 7708CB 8-Foot Chain Drive Extension Kit Features Fully compatible: the Chain Drive Rail Extension Kit for 8'-High Garage Doors is required for reliable, everyday operation of Chamberlain chain drive models in 8-ft. garage door applications. Easy Setup: featuring a quick-install extension rail and replacement chain, the kit includes all necessary hardware and instructions for a quick and easy installation. Includes one-year warranty, rail extension, replacement chain, all necessary hardware and an instruction manual for easy setup. Proven quality: rigorous quality testing ensures lasting performance. About Chamberlain: the largest and most dependable garage door opener manufacturer in North America. USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.