This is a Pentair 154512 Flanged Valve Wrench for 1-1/2 Inch MultiPort Top and Side Mount Valves on the Triton II Filters and Tagelus Filters. For models: Triton II TR100 and TR140, Tagelus TA30D, TA40D, TA50D, TA60D Filters.
The size is 6 Inches, 6-1/2 inches across flats.
