Heavy duty air hammer couplings have a coarse thread on the spud and wing nut and are interchangeable with other heavy-duty style couplings. Because they are not interchangeable with standard Viton® Seal Ground Joint Couplings and they are used extensively for Hydrocarbon drain hose applications petro-chemical plants. Always use the Coupling Selection Guide and Crimp Chart for more information regarding coupling choice and hose attachment.