The Klein Tools 21051C Replacement Blades safely remove the insulation on MTW, THHN and THWN-2 cable without nicking the wire. Users can simply insert the cable and twist for precise and clean cuts. This unit features cable sizes ranging from 250 MCM - 2/0 and 350-750 MCM. Users are provided with a tool that is designed for use with Klein 21050, 21051 large cable strippers.