Tap Bolts are fully threaded hex head cap screws or hex bolts.  They have a hexagonal head that is designed for a ratchet or spanner torque wrench.  This allows for tightening of the bolt.  Tap bolts are manufactured with different grades, finishes, sizes, and specifications depending on application.  A washer is commonly used under the head and the chamfered end and a nut is used matching up with the thread type of the hex bolt to exact specifications.  These fasteners are mostly used in construction, machine parts, and maintenance.