Hex head cap screws, commonly referred to as just "bolts", feature a hex head and come in coarse and fine threads. Metric hex cap screws use a DIN numbering system to denote fully or partially threaded. Grade 10.9 hex cap screws are made from quenched and tempered medium carbon zinc plated alloy steel. Grade 10.9 is comparable to imperial Grade 8. Grade 10.9 hex cap screws have a minimum tensile strength of 150KSI.