B-Line Eaton series Grate-Lock traction grip female to male interlock, 144" Grating length, 12" Grating width, Carbon steel, 2.5" Channel size, Galvan

This plank is the female/male interlock configuration: one long edge is formed female, the opposite edge male. Planks snap edge to edge so the seam locks mechanically instead of relying on fasteners between planks, which keeps the walking surface continuous at 12 inch increments of width.

That is what the traction grip surface is for. The plank is specified for safe, sturdy footing where non-slip is required, so it suits catwalks, mezzanine walkways, platforms and stair treads in plants where the deck gets wet or greasy.

The plank is 18 gauge carbon steel with a mill-galvanized finish. Mill galvanizing gives general corrosion protection for damp indoor and sheltered outdoor use, but the cut ends and any field-cut edges are raw steel, so touch them up with a zinc-rich coating. For continuously wet, coastal or chemical exposure, a hot-dip galvanized or stainless product is the better call.

Allow 2.5 inches. That is both the channel size and the overall product height, so the plank sits 2.5 inches above the top of your supporting steel. Factor that into finished walkway elevation, handrail height and headroom below.

It is sold as electrical-department support hardware and is the type of formed-steel plank used for walkways, platforms and stair treads around cable tray and equipment runs. It gives a non-slip 12 inch wide surface per plank. What it does not do is define your load rating for a given support spacing, so set your span from the structural design for the platform.