About the Hollow 6 mm Water Bottle Cage Bontrager???s Hollow Water Bottle Cage is formed using 6mm, hollow 6061-T6 aluminium tubing. This water bottle cage is lightweight and economical with a durable powder coat finish designed to keep it looking good. Key Features Constructed from 6061-T6 aluminium rod with two-piece bracket Durable powder coat finish Special design fits over front derailleur bands Weighs only 60 g Hollow tubing eliminates 15g without loss of strength About the Brand Trek Bikes began in 1976, and their mission was simple: Build the best bikes in the world. Today, Trek gives the brightest and most passionate cycling designers and researchers the resources to question everything. Because innovation happens only when you have the courage to ask the hard questions and go where no one has gone before. To lead, you must invent. Trek Factory Racing athletes compete at the highest level of their sport and inspire all to experience the grit and glory of professional cycling.