An open-ended head includes a first head jaw, a second head jaw and a head channel. The first head jaw extends widthwise between a first jaw flat and a first head edge surface. The second head jaw extends widthwise between a second jaw flat and a second head edge surface. The head channel projects lengthwise into the open-ended head. The head channel extends widthwise within the open-ended head between the first jaw flat and the second jaw flat. The open-ended head is configured from or includes a metal material. An adaptor is mated with the open-ended head. The adaptor is wrapped around the first head jaw and covers the first jaw flat and the first head edge surface. The adaptor is wrapped around the second head jaw and covers the second jaw flat and the second head edge surface. The adaptor is configured from or includes a polymer material.