3-1/2 in 3-piece couplings are used to connect 3-1/2 in threaded rigid or IMC conduits that are not able to be turned. Garvin Industries 3-piece couplings provide concrete tight connections. Garvin Industries heavy gauge construction maintains mechanical protection and solid grounding of one conduit to another. 3-piece couplings are zinc electroplated for excellent corrosion protection in damp locations.