BOTH ROUND & SQUARE HOLES: One side round holes beams are for sound equipment mounting with 10-32 screws, while the other side square holes beams are for rack shelves and 19” network equipment mounting with M5 & M6 screws STURDY TOP& BOTTOM PLATES: Half cabinet half rack designing, 4 post open frame rack with reinforced top& bottom vented plates, a good balance between air ventilation and firm structure, is convenient to put your laptop, laser projector, game console, CD player, or even a beautiful plant on the rack UPGRADED SUITE: RIVECO enthusiast 18u network rack suite meets your one-stop-shop needs. Including all necessary hardware: assembly screws & nuts, leveling feet and casters and one piece of 8 outlets PDU for daily usage VARIOUS SIZES: 19.7 " (500 mm) (W), 21.7" (550 mm ) (D), 41.4"（1050 mm with casters）(H). There are more sizes 6U, 9U, 12U,15U ,22U,25U to choose from HEAVY -DUTY: The 18u rack features high quality SPCC cold-rolled steel and excellent workmanship, this commercial & home rack can safely support maximum 500 lbs.（220 kg）of rack mounting equipment with leveling feet, and 400 lbs. (180 kg) equipment with casters. The black RAL9005 powder coat finish makes this solid 18 U home rack resistant to scratching and rusting RIVECO 18U floor standing server rack with one piece of rack shelf & PDU. We consider this series as of half cabinet & half rack, with top & bottom panels, but open frames sides. OFCO racks are widely used for electronics & equipment like AV, TV, NAS, DATA, server, internet router, amplifier, hard recorder, computer, X-box.