The Starrett SS 8.MA1X Square METRIC Gage Block Set contains 8 Blocks and includes accessories. Featuring 8 blocks 125mm, 150mm, 175mm, 200mm, 250mm, 300mm, 400mm and 500mm. Accessories included: 6 Each SA 8. Studs, 2 Each SA 9. Flat head Screws (long), 2 Each SA 10. Flat head Screws (long), 1 Each SA 16. 114-152mm Tie Rod (adjustable), 1 Each Sa 17. 152-228mm Tie Rod (adjustable), 1 Each SA 18. 298mm Tie Rod, 1 Each SA 19. 400mm Tie Rod and 2 Each SA 20. 502mm Tie Rods. This set has a B89.1.9 0 Accuracy Grade. Constructed of traditional high-grade Steel, which are generally used in shop floor environments.