This robust 5mm HTD 9mm wide aluminum pulley is a lightweight motion component thoughtfully designed specifically for FIRST Robotics Competition robots. It features a lightweight 2024 aluminum core, made from our 24 Tooth Aluminum Pulley Stock. Unlike other products on the market, this pulley uses super strong steel flanges that are formed onto the pulley body instead of using a traditional press fit for maximum flange retention and durability. This pulley has small bosses on each side that allow them to be installed against an FR8ZZ Round or FR8ZZ Hex bearing without rubbing on the outer races for smooth operation.Much like our 17 Tooth Magic Sprocket, this pulley is designed to fit perfectly inside a 2″ x 1″ aluminum box tube between two FR8ZZ Hex Bearings.