The Gage Assault Pack Add-on for PAYDAY 2 has 10 achievements.
In the Watchdogs job, complete the heist while you and your four man crew are wearing one different Assault Pack mask each on the OVERKILL difficulty or above. Unlocks the "Light Foregrip" for the Gecko 7.62 rifle, "Tactical Foregrip" for the Gewehr 3 rifle, "Long Barrel" for the Clarion rifle, "Void" material and "Death" pattern.