G&P Ultra Precision Gun Smith Gearbox Shim Set. (40 pcs)

"Best shims on the market, no question. Don't go for the Systema crap, the shims are mixed into a variation where they are in different sizes, in width and diameter. With these, you can make .6 mm shim with just three .2 mm ones. Only problem: easy to lose. Other than that (lol) they're cheap, great, and most of all, PRECISE.

"These shims are great if you are into an extremely precise level of gear shimming. I use them for all my AEG's. Having a properly and precicely shimmed gearset will allow you're weapon to perform better and use less energy.

"These are copper, would not recommend using for a gearbox. I wish I read the reviews and comments.