B-Line Eaton series imperial cable tray and ladder, 6" Height, 54.0625" Length, 30" Width, Series 2-5 horizontal bend, Aluminum, 90° Angle, 36" Radius

Plan for the fitting's 54-1/16 inch overall length dimension when you lay out the turn. The 36 inch radius is measured to the inside of the bend, and on a 30 inch wide tray the outer rail sweeps well past that, which is why the fitting comes in at 54-1/16 inches. Get those numbers on the drawing before you set your trapeze or wall bracket spacing, because a 36 inch radius sweep needs support on both legs coming out of the turn.

It is UL Classified. That is the designation UL uses for cable tray evaluated as an equipment grounding conductor and to the cable tray standard, and it is what an electrical inspector or a spec writer on an institutional job will be looking for on the fitting as well as the straight sections. Keep the classification consistent across the run: mixing a classified tray with an unclassified fitting undermines the grounding path.

What you are ordering under model 6A-30-90HB36 is the horizontal bend fitting itself. Splice plates, bolts, and any expansion or bonding hardware are ordered separately, and you need two sets, one at each end of the bend, matched to the Series 2-5 aluminum rail profile. Order those along with your hangers so the crew is not short at the turn.

Four things off the existing run: rail depth (this one is 6 inch), inside width (30 inch), material (aluminum), and the B-Line series, here Series 2-5. Those four decide whether the splice plates and rung pattern line up. Then pick the angle and radius your cable schedule needs, which for this fitting is 90 degrees at a 36 inch radius. Get the rail depth wrong and nothing bolts up.