175WR-4 Transducer Housing WrenchA single-handed wrench that holds the main thru-hull housing via the 'wrench flats' on the top of the housing to facilitate tightening of the hull nut. Use wrench 164WR-2 or 164WR-3 for the hull nut.For use with:B164B175SS164SS264IMPORTANT: the design of the housing for these transducers changed slightly in June 2012. This wrench is for the newer design and has an internal width of 2-3/4". If you need a wrench for the older designs then use the 164WR-4 instead, with an internal width of 2-7/16".