6 years ago I purchased a 12" (width x 20" (depth) under counter drawer made of pressed steel sides and a thin plywood base that sits on drawer sides and metal steel , which has been bent 90 degrees to provide a 1/2 "wide steel edge. Over the years, this box, despite only weighing a few grams, has fallen off the rails more times than I can remember. Due to Due to the fact that the steel is too thin, the sliders gradually slide off the sides of the box, allowing one to fall out of the side panels from the rim.There are also no ball bearings, just metal on metal.When I got these new extensions for keyboard drawers, I drilled 4 small holes in the steel edge and plywood that sat on each edge and used them to attach them to the steel edges at the bottom of each S side of my old drawer. Extensions on the underside of my laminate table. 2-3 times thicker than the original drawer slides, and the ball bearings and "stop" function ensure smooth sliding. Now I have the same box as before, but it's finally *sturdy*.