Excellent way to have a gun which can play in both CQB and Outdoor Field.
Pros:
+ Can adjust FPS between 250-440*
+ I find it delivers crisper blowback
+ Has tool for quick adjustments
Cons:
- Occasionally has large FPS variance (up to +/-20 fps)**
- At 'max fps' setting delivers lower fps than stock
- At 'low fps' can sometimes misfeed/sluggish blowback
* tested with 0.25 g bb with stronger floating valve spring, stock plastic nozzle, ratech trigger group and ratech bolt carrier, and 380 mm 6.03 inner barrel.
** fps variance is reduced with stronger floating valve spring