The SAT VVD is a 4 Stage Variable velocity piston with adjustment tool to regulate your FPS power! Adjustment can be made through the barrel by twisting the adjustable piston head to increase or decrease velocity! It's a complete plastic piston with full metal teeth. Made of high quality material and easy to install as any other piston. This VVD gives you full flexibility to use one AEG in both outdoor and CQB sites.

More info can be found at LCT Airsoft website: http://www.lctairsoft.com/