The SOCIMI Type 821-SMG is overall lighter and more compact than the Israeli UZI, weighing 2.450 grams unloaded vs. 3.500 grams of the UZI unloaded; and has an overall length of 400 millimetres with stock folded (vs. 470 millimetres) and 600 millimetres with stock unfolded (same as the UZI). The overall length reduction was achieved by shortening the barrel, using a 200 millimetres length vs. the original 260 millimetres. This has helped to achieve a slower rate of fire of 550 rounds per minute vs. the original 600 rpm of the UZI. Controllability in full-automatic fire results dramatically enhanced. Optimum results are obtained within a range of 150–200 metres, the telescopic bolt balances the weapon such that it can be fired one-handed with complete control.