Hex head cap screws are used to secure an object within or against another object. They have tighter tolerances, has a chamfered end and a washer face under the bolt head. The main difference between a hex cap screw and hex bolt is a hex bolt does not have a washer face under the bolt head. Bare metal fasteners have no corrosion resistant qualities and are a good choice for indoor and industrial applications where corrosion is not of concern. Grade 8: high strength for applications requiring superior load, tensile or shear strength such as heavy duty equipment or machinery. Made from medium carbon alloy steel quenched and tempered for stronger, safer more reliable mechanical joints. Six radial bars head marking. Tensile strength: 150,000 p.s.i. (min) use with Grade 8 nuts and washers to develop full strength of the cap screw. Double heat treated.