An all-purpose coupling, the female ground joint consists of a MALE STEM , WING NUT  and FEMALE SPUD . The female spud has NPT threads to accept the NPT threads of a rigid connection or male NPT nipple. Widely used for air, water or steam, the ground joint is secured with an interlocking clamp or ferrule. By replacing the female spud of a ground joint coupling with a double or male spud, hose-to-hose ground joint connections or hose-to-rigid connections are simplified. Double spuds for hose-to-hose connections are threaded NPS MALE X NPS MALE . (GJ wing nut is also NPS). For hose-to-rigid connection, the male spud is threaded NPS MALE X NPT MALE .