The Middle Atlantic DOOR-S12 is a solid door designed to be used with the Essex MMR Series. The door is capable of fitting both the front and rear of the Essex MMR Series racks. It provides a secure and enclosed space for equipment, protecting it from dust, debris, and other environmental factors. The door is sold individually and comes with all the necessary hardware for installation. It is easy to install and is a reliable and durable solution for securing equipment in a rack system.