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. The piston installs into a normal gearbox and then the tool can be used to adjust the valve setting from outside the gun (via the barrel).

This great new device can be used with V2 and V3 gearboxes.

It is worth noting that the VVD works best with higher powered spring, as the tests that were done on the device speak for themselves.

The testing was done on a standard M4, but it is worth noting that the below is just for guidance and will vary from gun to gun.

1.9 Joule Spring, 375mm Inner Barrel, 0.2g 6mm BBs.

• Position 1: 450 FPS (full power)
• Position 2: 340 FPS (20% drop )
• Position 3: 270 FPS (40% drop)

1.3 Joule Spring, 375mm Inner Barrel, 0.2g 6mm BBs.

• Position 1: 380 FPS (full power)
• Position 2: 315 FPS (17% drop)
• Position 3: 240 FPS (41% drop)

Included in the kit is 1 x piston and piston head and 1 x adjustment tool.

It is not recommended to use this on a high speed setup as we can not warranty incorrect use or installation."