Network Relay Rack, 2 Post, 42U, 45U, 48U, Aluminum or SteelDescription Network Relay Rack, 2 Post, 42U, 45U, 48U, Aluminum or Steel Primus Cable 2 Post Relay Racks are designed to work in a variety of rack system environments where a strong, stable, and durable relay rack is desired. The racks made of Steel or Aluminum options, and with a small footprint that saves floor space, this 2 Post Relay Rack provides unrestricted airflow for maximum ventilation and easy access to cables for moves, adds, and changes.