Genie's extension kit for tube belt drive rail is to be used in addition to a 7 ft. (5 piece) tube belt drive rail to accommodate an 8 ft. high door. This kit is designed for the Genie exposed belt garage door openers. This kit comes with everything needed to convert your standard 7 ft Genie garage door opener to fully lift your 8 ft high garage door. Kit contents: new longer garage door opener belt and snap together rail extension.