Specna Arms 7mm Bearings

Your bearing size is determined by your gearbox shell - if you have a 7mm gearbox then you can only use 7mm bearings, as no other size will fit. These are 7mm bearings, universally regarded as the best for general airsoft use.

Bearings increase in strength in relation to size; the larger they are the stronger they are. These bearings are manufactured by Specna Arms, and are fantastic value for money. They are low-noise and low-drag, making them perfect for medium to high ROF (rate of fire) builds. Bearings make the cycling of the gearbox smoother, and it removes stress from the axle of the gears. That said bushings are more reliable as they don't have any moving parts, so if your goal is sheer reliability then you are better off with bushings.

Fitting bearings to your gearbox requires complete disassembly - if you are at all unsure, please seek the aid of a professional