Hellermanntyton fittings for metallic conduit with plastic coating psc fm series hellermann tyton 166 31004 the hellermanntyton 166 31004 pcs20 is a conduit fitting with a m20 fixed external thread for plastic coated metallic conduit from the pcs fm series the conduit fitting comprises of two parts the shell and the body the connector has been manufactured from nickel plated brass hellermanntyton 166 31004 psc20 fm m20 helaguard metallic conduit screw fitting