B-Line Eaton series open racks, Universal spacing, Steel, Telco gray powder coat, 12-24 panel mounting holes, 58 mounting spaces, Top channel style,

58 mounting spaces, which is 58 rack units of usable mounting height on the Eaton B-Line SB5856108UTG. The frame stands 108 inches tall overall, so the difference between overall height and usable RU is the top channel and base. Plan cable management and any shelf-mounted gear within that 58U.

The SB5856108UTG is built as a Seismic Zone 4 rack, which is the highest of the legacy seismic zone classifications and the one that covers most of coastal California. That rating only holds if the frame is floor-anchored as intended, so the anchors and the slab detail are part of the install, not an option.

The rails are punched with 12-24 panel mounting holes in universal spacing. Any switch, patch panel, or rack shelf that ships with 12-24 rack screws goes straight on. If your gear came with 10-32 screws or expects square-hole cage nuts, you need 12-24 screws instead, since the holes here are threaded for 12-24.

An open frame like the SB5856108UTG gives you access from all four sides and unrestricted airflow, which is why it is the standard in telecom rooms, MDFs, and secure IDF closets where the room itself is the enclosure. Choose an enclosed cabinet instead when the equipment sits in a shared or public space and needs to be locked, or when it needs dust and contamination control. Open frame also makes overhead cable routing far easier, and the top channel on this one is there to tie into ladder rack and runway.

UL Listed is stated for the Eaton B-Line SB5856108UTG open frame rack, which is what spec writers and inspectors generally want to see on the frame itself for institutional and healthcare telecom rooms.

Closed duct unequal flange refers to the rack upright profile. The closed section adds torsional stiffness for the seismic rating, and the unequal flanges give you a deeper face on one side for equipment mounting and a shallower one for cable routing and clamps. Practically, it means the SB5856108UTG carries heavy gear without the uprights twisting, and gives you a flange to strap vertical cable bundles to.

Steel to ASTM A1011SS, finished in telco gray powder coat. That gray is the long-standing standard color in telecom and central office rooms, so it lines up visually with existing telco-gray racks and ladder rack rather than standing out. The frame weighs 91.25 lb bare.