Nut Thread is 3/8" Compression Overall OD: 0.80" Pipe ID: 0.30" Pipe OD: 0.42" Heat Sink Metal Fins 16" Long Note: The main line that carries compressed air from the pump head to the air tank, the discharge (or “transfer”) tube is typically made of copper, aluminum or stainless steel braided material. Be sure all compression fittings and threads have tight seals and don’t leak, and replace if kinked or cracked.