The revised HE valve reduces the air wasted when venting to unbalance the spool. And the QEV plays a role in maintaining cycling time - also making it more difficult to short stroke. Players will experience a dramatic increase in efficiency - in the range of 30% or more. The HE (high efficiency)valve is a upgrade over the previous generation HD (heavy duty).
The HD Valve is the version that has been the workhorse for the past several years that you’ve seen before. The HD is still standard on all rental and retail eNMEy.