Submachine Gun Mods & Upgrades - Mass Effect 3 wiki

SMG Heat Sink - Increases heat conductivity of thermal clip receiver. Negates heat generated by some shots.

SMG Magazine Upgrade - Increased magazine capacity means more shots, fewer reloads.

SMG Scope Upgrade - Simple 2x optical scope enchances stability while zoomed. Increases accuracy while moving and taking damage.

SMG Ultralight Materials - Superior lightweight alloys replace weapon parts, making weapon less obtrusive and easier to handle.