The only thing that could be better is 9mm bearings ! These bearings are high quality , and increase the efficiency of your weapon dramatically . The reduction in friction verses bushings will increase your battery life dramatically , as well as reduce overall strain on your gearbox . 6mm bearings are too small to be manufactured to the accuracy level of 7 or 8 mm , and will fail much more quickly that expected . I put these 8mm bearings in my Cyma AK74 Krinkov and they nearly doubled my battery life . I did have to modify the safety linkage , but it was an easy mod and the weapon RIPPPS! Bearing are usually not recomended for very high ROF guns as , they will burn up rather quickly due to the small size , but if high FPS is your objective , these are the way to go .