175WR-4 Transducer Housing Wrench. A 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 B164. B175. SS164. SS264. IMPORTANT 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 . A single-handed wrench that holds the main thru-hull housing via the 'wrench flats' on the top of th For use with . B164 B175. SS164 SS264. IMPORTANT the design of the housing for these transducers changed slightly in June 2012. Thi