High grade alloy steel. Metric size cap screws with hexagon recessed heads. Handy kit for shop toolroom or toolbox. On hand when needed saves time and money. Plastic compartment box is easy to store. The Precision Brand 255-piece metric socket head cap screw Assortment contains 25-piece each of: M4x0.7 by 10 mm, 12 mm, 20 mm and 25 mm, M5x0.8 by 12 mm and 20 mm, 10-piece each of M5x0.8 by 25 mm and 30 mm, M6x1 by 12 mm, 20 mm, 25 mm, 30 mm and 40 mm, M8x1.25 by 20 mm, 25 mm and 30 mm, 3-piece M8x1.25 by 40 mm and 2-piece M8x1.25 by 45 mm.