Bulkhead D.O.T. Compression couplers, also known as terminal bolts or anchor bolts, are similar to standard bulkhead frame couplers in that they are made to attach to a panel or frame so that air can pass through but they feature a built in compression tube connector to make connections sealed and quick. They feature a brass body and nut for high corrosion resistance and a steel internal tooth lockwasher to anchor it in place when tightened.