BOLT SCREW HEAD TYPES . SLOT PHILLIPS hereBO SQUARE hereBO PHILLIPS HEX HEAD SLOTTED HEX SIX LOBE TYPES OF BOLT AND SCREW HEADS PAN HEAD : heremended for new designs to replace round, truss and binding heads . Information on Fastener Materials; Reference Guide to Finishes Plating; Identifying Bolt Screw Head Types ; Screw Point Types ; Screw Thread Pitch Table; Drive Tool Size Chart; herepatibility; Flat Washer Thickness Table; Metric Conversion Information Types of Screws Heads . Basically, screw heads are divided into 2 categories. Countersunk Screw Head ; Non-Countersunk Screw Head ; For an instance just look at the head of the screw , and you will find that in the first one there is an angular shape underneath (Below) the head and in the second one there is a flat shape.