Will hold itself to metal surface and varied shaped work pieces to allow light machining operations All the contact faces of this magnetic V block are precision ground flat and smooth. Contact surfaces are hardened. All the contact faces of this magnetic V block are precision ground flat and smooth. Contact surfaces are hardened. This V block will hold itself to a flat metal surface, and will also hold varied shaped work pieces so that light machining operations such as grinding, boring and tapping can be performed with minimal set up time. Will hold round stock up to 2" in diameter. This block will exerts a magnetic attraction to the upper, lower and V-channel surfaces. Magnet has an On/Off switch which easily and quickly engages / releases magnet. We are the leading mftr. of hand tools,v