Bontrager 6mm Bottle Cage Bontrager's standard bottle cage is constructed using 6mm, hollow 6061-T6 aluminum tubing to produce a lightweight & economical cage. It fits any frame with standard bottle cage mounts & features a durable powder coat finish to keep it looking good for longer.6061-T6 aluminum rtubing Standard, universal two piece bracket Durable powder coat finish Special design fits over front derailleur bands Easy, 30 second installation Limited lifetime warranty Hollow tubing cuts weight without loss of strength Weight 58 grams