B-Line Eaton series imperial cable tray and ladder, 6" Height, 24" Length, 18" Width, Series 2-5 horizontal tee, Aluminum, 12" Radius

Yes. The 6A-18-HT12 is built for 18 inch inside width tray with a 6 inch side rail height, so it mates to a Series 2-5 aluminum ladder run of that same width and depth. All three legs of the tee are the same 18 inch width, so the branch run has to be 18 inch tray as well. If your straight sections are a different width or a 3, 4, or 5 inch rail, this fitting is not the one.

A horizontal tee handles a three-way intersection in the same horizontal plane, one straight run with a single branch off the side. If cable leaves in two opposite directions off a single run, that is a four-way intersection and you want a horizontal cross. If the branch drops or rises out of plane, neither one applies, you need a vertical elbow or a tee in the vertical plane. The 6A-18-HT12 is the three-way horizontal fitting.

Aluminum. That is the usual choice for wet, coastal, or chemically aggressive environments where galvanized steel tray would need extra protection, and it cuts the dead load on the supports. It also means you should keep the fitting hardware and any adjacent tray consistent in material to avoid dissimilar metal contact at the splice plates.

Figure 6 inch height, 24 inch length or depth, and 18 inch width, with a 12 inch radius on the turn. Use the 24 inch dimension when you set out where the straight sections stop on either side of the intersection, and cut your straight tray to suit rather than trimming the fitting.

The 6A-18-HT12 weighs 15.129 lb. Light enough for one person to set on the run, but the intersection still needs support on each leg near the fitting per your tray support spacing, because the tee concentrates cable load where three runs meet.