Antre du Dingo Dingchavez review the SAT Variable Velocity Device which allows you to adjust the power of your AEG without any need for a spring change... "There's no QC spring system on your AEG? You're fed up with having to swap for a lighter spring every time you go to CQB? Here is a solution to your problem: the Variable Velocity Device. A piston and a piston head that can be adjusted on the fly!"

Those looking for this in the UK can get this at Action Hobbies for £79.99... "The Variable Velocity Device or VVD is a set that includes a piston and piston head as well as an adjustment tool. The piston has head venting that can adjust to three different positions to alter the air flow to adjust the power generated.