CRL Combination Exchange Windows are two-lite units, one full height and one secured above the package pass-thru. The 36" x 36" (914 x 914 mm) standard size unit is available with a choice of Clear Package Receiver or Rotary Server. The 18" (457 mm) deep bullet resistant shelf is covered with a black plastic laminate, and is included in the 36" frame height. Both units come with a Level 1 Non-Ricochet Bullet Resistant Deal Tray. Perimeter frame is our Standard Inset Frame, and requires a wall thickness of at least 4-7/8" (124 mm). Glazing is 1-1/4" (32 mm) bullet resistant Level 1 Acrylic. Available frame finishes are satin anodized or bronze anodized. Voice transmission is accomplished with Surround Sound. The standard unit is recommended for interior use. Exterior models and custom sizes are available on special order.