Jagwire 5mm POP End Cap for Compressionless Brake Housing Bottle of 10 Black. POP end caps are designed specifically for use with 5mm compressionless brake housing. Not all frames or brake calipers are designed to accept a standardized end cap so the POP end cap acts as a reducer.

Reducer end fits brake calipers and frames that are not designed for normal end caps

Durable alloy construction resists the increased stresses of compressionless brake housing