INSIZE V-Block Set Sold as 2 Matching V-Blocks per Set, made of alloy steel, hardened to HRC60+2. Hold cylindrical workpieces for inspection and machining. Specifications include... Size: 2.8" x 5.5" x 5.5" Holding Range: 0.35" - 5.51" Parallelism of both V-Grooves to top and bottom sides: 197µin Squareness of both V-Grooves to front and back sides: 197µin