4 in are used in wet locations to connect the ends of two 4 in EMT thin wall conduits together to extend the raceway . Garvin Industries' rain tight steel EMT compression couplings have been designed to comply with the new rain tight test requirements along with the 2008 NEC 358.42 and 314.15 requirements. Garvin Industries' heavy gauge steel construction maintains mechanical protection and solid grounding of one conduit to another. Compression couplings are zinc electroplated for excellent corrosion protection in damp locations. Garvin Industries' rain tight EMT compression couplings come with the fitting pre-assembled making them ready to install on the conduit. Rain tight compression couplings are installed like any other steel EMT compression fitting and require no special tools.