The 254PW20E0152-S1S1 is part of the Nicomatic 254 Series of high-density, keyed, plastic connectors. This particular version has a 20-way pitch of 2.54mm, a 3A current rating, and housing material made of polyester. It includes two pieces: a male (pin) header and a female (socket) receptacle. It is well-suited for applications that require compact size and secure interconnections.