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 Asst contains 25 pieces each of: M4 x 0.7mm by 10mm, 12mm, 20mm, and 25mm; M5 x 0.8mm by 12mm and 20mm; 10 pieces each of M5 x 0.8mm by 25mm and 30mm; M6 x 1.0mm by 12mm, 20mm, 25mm, 30mm, and 40mm; M8 x 1.25mm by 20mm, 25mm, and 30mm; 3 pieces M8 x 1.25mm x 40mm; and 2 pieces M8 x 1.25 x 45mm.