Precision V-Block & Clamp Set - Multi Use, Multi-Use : Holds both Square and Round Work. Stepped Groove Construction permits both Low and High Clamping. Side Hole-Provided in each block to facilitate clamping. Made of Hardened Tool Steel, Machined and Ground in Pairs. All Sides Precision Ground Parallel and Square to an accuracy of 0.0003". Set Consists of Two V-Blocks and Two Clamps. Capacity : 2" (50 mm) Round and 1-716" (36.5 mm)