The PDI FPS Tuning Set is a kit of 5 Delrin washers. These are designed for use with PDI upgrade springs, and fit on 9mm spring guides for both VSR-10 and APS2 or Type 96 rifles.
By adding shims, the velocity of your airsoft sniper rifle can be precisely adjusted to add a small boost without needing to jump up to the next spring rate. These are also ideal for use as a thrust washer on the spring guide to prevent metal on metal wear of the upgrade spring on a stock or upgraded spring guide.
PDI FPS Adjustment Thrust Washer Set Features:
-Precisely Adjust FPS
-Doubles As Thrust Washer