A screw-in, cartridge style, pilot operated (2-stage), spool type, normally closed, hydraulic relief valve. When the pressure at the Inlet (1) reaches the valve setting, the pilot poppet starts to open from its seat and determines the shifting of the main stage poppet (spool type) that throttles oil flow to tank (2). There are options for two pressure setting. One is Main stage pressure setting, that is called nominal setting. Second is Pilot stage pressure setting. It can be activated with esternal hydraulic pilot pressure on port 3. The cartridge offers smooth transition in response to load changes in demanding hydraulic circuits. Fast, smooth response and limited hysteresis. Warning: Adjustment screw doesn’t have a positive stop which prevents it from being backed out of the valve. Metric cavity.