Pentek SW-3 # 150296 SW3 Big Blue Water Filter Housing Sump Spanner Wrench Compatible With Culligan, Ametek, US Filter, Plymouth, Kleen Plus, American Plumber, Bruner & Many Other Brands. SW-3 Big Blue 5 7/8" Water Filter Housing Sump Spanner Wrench. (Big Blue Filter Housings Use A 5 3/4" Diameter O-Ring) Ametek # 150296. Only for use in loosening sumps on filter housings, never to tighten. Overtightening may cause damage to the O-rings and make re-opening VERY difficult. Hand tighten only. For really stubborn filter housings our technicians will use two wrenches together for maximum power where one wrench might break or not do the job. Our pure water techs know the tricks.