I bought one of these about three years ago to replace a faulty ballast in an under cabinet light in my kitchen. I was a little worried about the fit as I only had about 1 inch of thickness in the mount and couldn't find the measurements on the Revain. I found the sizes on one of the manufacturer's sites and bought them. Based on my tape measure, it's only less than 1 inch thick. The ballast worked so well that last year when another ballast from the manufacturer failed I ordered three. Easy install, they work great and haven't had any reliability issues with two installed so far.