PACKAGE RECEIVER WITH BRUSHED STAINLESS STEEL DOOR PROTECTION LEVEL 1 and LEVEL 3. Interlock Security on Doors, Custom Sizes and Features Available-designed for the transfer of larger items. A special interlocking mechanism between the interior and exterior door allows only one door to be opened at a time. A separate bar lock for the exterior door can be activated from the inside. A closer is furnished on the exterior door.The unit will mount in walls up to 11-1/2 inch thick,and requires a 15-1/2 inch wide x 15-1/2 inch high wall opening.Units are available with prime painted housing and prime painted doors,or with prime painted housing and stainless steel doors.