Our pulley wheel listing name follows the format: Upper Wheel Tooth Count / Lower Wheel Tooth Count + Wheel Material + "Pulley Wheels" + Rear Derailleur Brand + Speed + Road/Gravel/MTB Options. For example, 11/11T Delrin Pulley Wheels - Shimano 10/11/12 Speed Road refers to pulley wheels with 11 teeth each, made from Delrin, designed for Shimano rear derailleurs (105, Ultegra, Dura-Ace, etc), and compatible with 10, 11, and 12-speed drivetrains. When selecting, first choose the rear derailleur brand and speed from the available options, then decide on the tooth combination and wheel material. Each listing includes a comparison of tooth combinations and material features in detail.