Square Head Bolts are similar to Hex Cap screws but have a 4-sided square head instead of a 6-sided hexagonal head. The square head enables an easier wrench grip for tightening and a larger bearing area for gripping. They are commonly referred to as both bolts and screws and are designed to be driven with a wrench. Square Head Bolts are partially threaded with a shoulder beneath the head.
||M6 to M20
|| Black Oxide, Zinc Plating, Hot Dip Galvanized
||4.6, 4.8, 5.6, 5.8, 8.8, 10.9, 12.9