Profile: Barnhill Bolt Co. carry nuts, bolts and all kinds of industrial fasteners. Our product line includes clip, pins, rings, drill bits, socket screws, strut and fittings, taps & dies, inch, threaded inserts, vented screws, washers and weld studs. Our hitch pin clip also known as hairpin clips, these spring-style cotter pins are ideal for quick assembly and disassembly. Our hispeed steel bit, extra long is designed for drilling shallow holes in hard-to-reach spots.