An SPM valve (10) for use in a subsea environment includes a spool (34) selectively movable between first and second positions to thereby arrange the valve (10) in respective armed and disarmed configurations. The particular arrangement of a supply port (22) and discharge port (24) with respect to the spool (34) permits a pressurized working fluid ("F") supplied to the supply port (22) to bias the spool (34) to both the first and second positions once an external force is applied to the spool (34) to initially set the spool in either the first or second position.
