Large old aluminum Tri Clover open ended wrench. This wrench is marked "Tri Clover - 25H-3 - Kenosha, Wisconsin". It was made for using with the stainless steel fittings on dairy farm milk bulk tanks, milking pipelines and related food grade stainless steel equipment.
Aluminum was used for these wrenches as aluminum is much weaker then stainless steel, so if the fittings became stuck too tight, the farmer would bend or break the aluminum wrench before the threads on the stainless dairy fittings would be striped.
Walker 8 Hex Wrench CAB1543 3" Wrench Used Plant City, FL