Round Head Stove Boltis also known as machine screws. It is used to fasten metal parts together that are going into a tapped hole, or through a hole and being held by a nut. It is common used along with wood to metal and wood to wood. Round Head Carriage Bolt is a bolt with threading all the way up the shank to a small square shoulder, with a domed head. It is used to fasten metal to metal or metal to wood. It is used extensively in security fixings, such as hinges and locks, where the bolt must be removable from one side only.