These hex bolts have hexagonal heads and are for general purpose applications with a socket type installation tool or standard wrench. The standard bolt is compatible with standard nuts and washers of the same thread pitch, grade, and finish. Grade-8 bolts have a higher strength and are to be used with Grade-8 nuts. An alternative for using hex bolts without nuts is to place them directly into a compatible female threaded receptacle. They require a pre drilled or pre-tapped with compatible female thread. Available in various materials, grades, and finishes.