B-Line Eaton series imperial cable tray and ladder, 4" Height, 19.188" Length, 30" Width, Series 2-5 vertical inside bend, Aluminum, 90° Angle, 12" Ra

It turns a cable tray run 90 degrees in the vertical plane, bending toward the inside of the tray (cables run along the inner curve). It's a Series 2-5 aluminum fitting sized for 30 inch wide, 4 inch deep tray, with a 12 inch bend radius. Use it where a horizontal run has to drop or climb, for example coming down a wall from an overhead run.

Inside versus outside is about which way the tray turns relative to the cable. A vertical inside bend, like this 90 degree 12 inch radius unit, curves so the cables lie on the inside of the arc, typical where a run drops down from a ceiling-level tray. If the run has to rise up and over an obstruction, with cables on the outer face of the curve, you want a vertical outside bend instead. Same width and depth apply either way.

It is UL Classified. The aluminum construction also makes it a common pick for corrosive or damp environments and for runs where a steel fitting's weight is a problem. As an aluminum tray component it can serve as part of the grounding path only where the installation and cross-sectional area meet code, so confirm with your bonding plan.

Plan on it. The 4A-30-90VI12 is the bend section itself; the splice plates, hardware and any hangers or supports at the bend are ordered as separate items. Match the splice plates to Series 2-5 aluminum tray at 4 inch rail depth so the bolt pattern and rail profile line up.