As soon as you’ve stocked up on cards, go to the police storage. For mopping up the location, you’ll get reward conveyor access cards. They can be of 4 grades: sergeant, captain, lieutenant and inspector. You can use cards to get a box with rewards in the armory. The higher the card grade is, the better the reward. The number of tries a day is limited. Rewards can be various: firearms, armor, blueprints and unique resources for weapon modification and other resources and parts.