They are bolts with cylindrical head recessed key used in cases where the seat of the imbus bolt head is too narrow for the nut wrench to enter, or in cases where the bolt head is not wanted to be left out. Also known as Allen head, hex head or hex head bolts. They are used with an Allen key. Allen wrench is a simple tool used to drive bolts and screws with hex socket heads. The tool usually consi...
View
