B-Line Eaton series imperial cable tray and ladder, 4" Height, 13.25" Length, 18" Width, 18" and 9" Tray widths, Series 2-5 right reducer, Aluminum

It transitions an 18 inch wide tray down to a 9 inch wide tray. The offset is on the right side, so one side rail stays in line and the reduction happens on the other. Height is 4 inches, matching a 4 inch deep tray run, and the fitting is 13.25 inches long.

The 4A-18-RR09 is the right-hand version, meaning the reduction is taken out of the right side while the left rail runs straight through. Sight the run in the direction of the reduction: if the narrower 9 inch tray needs to stay flush with the left rail, this is the fitting. If it has to stay flush with the right rail, you want the left reducer instead, and if the 9 inch section should center on the 18 inch run you want a straight center reducer.

It is a Series 2 through 5 fitting, so it suits B-Line imperial ladder tray in those series at 4 inch rail height. Order it by the part number 4A-18-RR09 to get the aluminum 18 to 9 inch right-hand reduction.

The part supplied is the reducer section itself, 18 inches wide at the large end and 13.25 inches long. Splice plates, connecting hardware, and any supports at the transition are separate items, so add a set of splice connectors for each end when you order.

3.2 pounds. That is light enough for one electrician to set on a trapeze or threaded-rod hanger without a second pair of hands, which is one of the reasons aluminum tray gets specified on long overhead runs.