Specna Arms 8mm Bushings

Your bearing size is determined by your gearbox shell - if you have a 8mm gearbox then you can only use 8mm bushings or bearings, as no other size will fit. These are 8mm bushings, universally regarded as the best size for general airsoft use.

Bushings are louder than bearings, however as they have fewer moving parts, they are more reliable (and more durable)

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