PFD21 1" Deep Plexiglass Door for 21RU 100, and 200 Series Racks made by Atlas Sound is designed for the installer Atlas Sound's PFD Plexiglass Doors look great and install easily. This door fits the 100, and 200 Series Racks. The inovative design of these cabinets includes gripsert hardware. This allows the installer to mount the door without the typical nut and bolt style hardware. meaning you can mount a door on a cabinet already filled with gear.