Item Type: Bike Rear Derailleur Pulley Screw. 2 x Bike Rear Derailleur Pulley Screw. Feature: 1. TI ALLOY, LIGHTWEIGHT: This screw has been built with selected premium ti alloy, which significantly reduces the weight of the screws compared to traditional materials, helping to improve the lightness and acceleration of the whole bike, and allowing for a more flexible ride.