TE Connectivity Series 1 CPC Connectors, One-Piece Sealed Series 1 sealed single piece circular plastic connectors made from UL 94V-0 black thermoplastic with a pre-installed, bonded peripheral seal made of grey elastomer. This Series 1 sealed circular plastic connector range consists of square flange receptacles, free-hanging receptacles and plugs, please refer to table for details. The square flange receptacle versions of these Series 1 circular plastic connectors use flange seals, see stock numbers 362-4429, 362-4441 and 362-4457 typically.