This mod drastically reduces the noise created by firing a round. Visually, a suppressor is fixed to the muzzle of the sniper rifle. While in sneak mode, the suppressor allows the player to assassinate targets while minimizing the chances of alerting nearby NPCs. This makes it highly useful for killing single targets without drawing attention to oneself.
Prior to patch 188.8.131.522, the sniper suppressor was only worth 250 caps.