Materials and durability - Made of engineering plastics for durability and long life Function and compatibility - Designed for wiring embedded card holders and frames with a single hole - Embedded length in frame: about 20 mm (0.79 in); width: about 8 mm (0.31 in) Protection and performance - Effectively protects brake/shifter housing from wear caused by frame holes - Helps extend cable life and reduce maintenance Package contents - 20 pcs Bike Brake Shifter Housing Grommets Use scenarios - Internal cable routing on frames with a single routing hole to prevent edge wear on the housing - Upgrading or retrofitting frames for internal routing to improve wear resistance - New bike builds requiring protected routing through a single frame hole for brake/shifter housing Notes - Keeps compatibility simple: suitable for standard internal routing setups that use a single frame hole.