Crupi Solo Chain TensionerPRODUCT DETAILS These cutting edge tensioners are CNCd from 6061 T6 aluminum and feature a revolutionary single screw adjustment system. Unlike some chain tensioners, the Solos use a proprietary 2. 5mm single adjusting screw that operates independent of a C ring or Clip device, allowing for smooth and reliable adjustment of your drive train every time. With only two moving parts, these are one of the most reliable and convenient chain tensioning