B-Line Eaton series imperial cable tray and ladder, 4" Height, 9.78" Length, 24" Width, 24" and 18" Tray widths, Series 2-5 straight reducer, Aluminum

It transitions a 24 inch wide cable tray run down to an 18 inch wide run in a straight line, keeping the run on the same centerline. Tray depth is 4 inches on both sides, and the reducer section itself is 9.78 inches long, so plan that much added length into your run.

Aluminum. That keeps the piece light, 2.9 lb for the section, which matters when a single electrician is holding it up on a ladder to bolt into the run. It also means you should keep the rest of the run and the hardware aluminum to avoid mixing materials in a corrosive or outdoor environment.

Order Eaton B-Line 4A-24-SR18. The number reads out the spec: 4 inch depth, aluminum, 24 inch incoming width, straight reducer to 18 inches.

A straight reducer like the 4A-24-SR18 steps 24 inches down to 18 inches symmetrically, so both side rails move in and the run stays on the same centerline. Use it when the tray centerline has to stay put. If one side rail has to stay flush, for example running tight along a wall or lining up with a piece of equipment, you want a right hand or left hand offset reducer instead, not this one.

9.78 inches. When you are cutting the straight sections either side of a width change, take that off your layout so the reducer lands where the drawing shows the transition.

It is CE marked. No other rating is carried on the 4A-24-SR18 record, so if a project spec calls for a specific listing beyond that, verify against the manufacturer submittal for the series.