Manual Lowering Valve (with blue o-ring) for many Rotary power units, including those using an UP100K7 Pump.

This lowering valve can be found on various hoists including the SPOA10 (700 series) with an FA7147 motor.  Pumps that use this type of lowering valve will typically have a separate (independent) check valve.  If the check valve is built in with the lowering valve, it could be this part instead.