B-Line Eaton series imperial cable tray and ladder, 4" Height, 9.78" Length, 12" Width, 12" and 9" Tray widths, Series 2-5 right reducer, Aluminum

It's a right-hand reducer fitting that steps a 12 inch wide tray down to a 9 inch wide tray in a straight run. The reduction happens on one side only (the right), so the opposite side rail stays in line. That matters when you're keeping one edge of the tray flush against a wall or following a single alignment line through a building. Overall it measures 4 inch height, 12 inch width, 9.78 inch length.

Handing on a tray reducer is read looking along the direction of the cable run. On the 4A-12-RR09 the width comes off the right side as you face downstream. Because the fitting steps from 12 inch down to 9 inch, flipping it end for end reverses which side is wide but also reverses the flow direction, so it does not convert it into a left reducer. Order the handing that matches your layout drawing.

The 4A-12-RR09 is supplied as the reducer fitting itself. Splice plates and their hardware are separate items on B-Line tray systems, so order the splice connectors matched to your Series 2-5 aluminum tray along with it if you don't already have them on site.

2.2 lb. Aluminum construction keeps it light enough that a single installer can hold it in place on a trapeze while splicing, and it adds almost nothing to the hanger load compared with the cable fill itself.

This reducer is aluminum, which is the usual pick where weight matters or where mild moisture and washdown would attack painted steel, and it needs no galvanizing. For heavy industrial corrosives or where a spec demands a specific coating system, the equivalent fitting in steel or stainless is the substitution to chase instead. The aluminum version is also the lighter option for long overhead runs at 2.2 lb per fitting.