'SATGURU' Steel V-Blocks are made of tool steel, hardened, tempered & precision ground on all sides. Both sides 'V' with one clamp 1. Unbreakable Steel Clamp. 2. All Hardened & Tempered 52-56 HRC. 3. Parallelism & Squareness of all faces & āVā within +- 0.005mm. 4. Inspection certificate is furnished.