6A opening with communication adapter on one side. Accommodates Wiremold Open System communication modules. NOTE: Four-piece service fittings include: housing and base plate. Receptacles included when indicated in part number description. 525 Series Service Fittings have 27 cubic inches (442ml) of capacity. NOTE: Four-piece service fittings include: housing and base plate. Receptacles included when indicated in part number description. 525 Series Service Fittings have 27 cu. in. (442ml) of capacity.