Keys for 4C mailboxes with parcel lockers can be found in the left-side parcel locker, along with the hardware and installation instructions. To open the parcel lockers, reach into the center of the unit and push on the bracket located in the upper left corner. This will open the right-side gate and allow you to open the left-side gate, giving you access to the left-side parcel compartment. Keys for 4C mailboxes without parcel lockers can be found in one of the tenant door compartments along with the hardware and installation instructions. Note: Before completing the following steps, please make sure your 4C unit is securely placed on a flat surface so it does not fall over when the master front door is open.