B-Line Eaton series imperial cable tray and ladder, 6" Height, 9.78" Length, 12" Width, 12" and 9" Tray widths, Series 2-5 left reducer, Aluminum

A left reducer is the transition fitting used when a cable tray run steps down from one width to a narrower width. The Eaton B-Line 6A-12-LR09 makes that step between a 12 inch tray and a 9 inch tray, with the offset taken on the left side so one side rail stays in a straight line. Use a left reducer when you want the run to stay flush along the left rail (for example against a wall or alongside a parallel run); use a right reducer when the straight side needs to be the other rail, and a straight reducer when you want the reduction split evenly on both sides.

It joins a 12 inch wide tray to a 9 inch wide tray. If your run steps from 12 to any other width (12 to 6, 18 to 12, and so on), this is the wrong fitting, since a reducer is built for one specific width pair.

Stand in the run and look in the direction the cable is heading, from the wide tray toward the narrow tray. If the offset falls on your left and the right rail continues straight, that is a left reducer, which is what the 6A-12-LR09 is. Getting it backwards means the straight rail ends up on the wrong side and the fitting won't sit flush against the wall or the adjacent run.

Plan on 9.78 inches of run length for the reducer section. That is the dimension to subtract when you cut or order your straight sections on either side of the transition, so the support spacing and splice points still land where you laid them out.

Aluminum. That keeps it light, 2.8 lb for the fitting, and it is the usual choice where corrosion resistance matters or where crews are handling long runs overhead. Match it to aluminum tray and aluminum splice hardware so you are not mixing dissimilar metals at the joint.

It is UL Classified. That is the designation to cite on an electrical inspection for a cable tray fitting in a commercial or industrial installation.

The 6A-12-LR09 is the reducer fitting itself, a Series 2-5 aluminum left reducer. Splice plates and bolt hardware for the two connections are ordered separately, so add the correct B-Line splice kit for your tray series and rail height when you order the fitting.