Granite parallels:BoHai parallels can be used to elevate workpieces above the surface of a plate so the workpieces with shoulders or steps can be puickly and easily inspected among many other uses. They come in 2 sides finished or 4 sides finished. Always supplied in pairs. Our standards mainly according to GB87-85, GGG-P-4630, DIN876, JIS-B510, ISO-DP8512 and so on. This item are available in grades”000”,"00" and"0", Manufactured from carefully selected black granite.