1 1/2 inch NH / NST barrel strainer with poppet style foot valve. Female threads do not swivel. NH / NST threads are used by most fire departments.
A foot valve is essentially a check valve. It's usually installed on the inlet side (Suction Side) of a water pump to keep it from losing it's prime during the off cycle.
This Wildland Fire Equipment foot valve is used by the U.S. Forest Service (USFS), Bureau of Land Management (BLM), Bureau of Indian Affairs (BIA), U.S. Fish & Wildlife Service (USF&WS), National Park Service (NPS), State and Local governments, and other Forest Service–sponsored participants in the government-wide wildland firefighting effort.
This is the same water-handling accessories forestry wye valve found in the Defense Logistics Agency (DLA) Wildland Fire Equipment catalog or Fedmall.mil.