3/8" X 2-1/8" conveyor coupling bolt is a type 4 X 1 #4 bolt manufactured out of high-grade high-strength steel to achieve the required performance for the application it was intended for. Screw conveyor assembly bolts are designed with a hex head machine bolt with lock washers and a hex nut, and they are made to precise dimensions to ensure proper fitment when installed. For additional information or to get a quote on assembly bolts or other screw conveyor parts, contact our customer support team, and we will be happy to assist you!