Free mask for Payday 2 - just follow the instructions on the site and voila.
Basically, you must have the base game in your library and log in via Steam.
There are other items that are permanently free in case you missed them so far:
- Housewarming Party Hat DLC: https://www.overkillsoftware.com/housewarmingkeys/
- Fedora DLC: https://www.overkillsoftware.com/fedorakeys/
- Pencil (melee weapon) DLC: https://www.overkillsoftware.com/kentokeys/
Mod Note: Locke & Load 'SIMON' MASK now out of stock. Rest still available.