Nice replacement for my old plastic tray under the desk keyboard that was always flexible. I made a shelf from an oak board, now it's very durable. However, I give a few stars because of a bug. When fully extended there is a small latch to keep the rails extended and provide some resistance to the shelf sliding back too easily. However, they are very flimsy and will weaken after some use, so now if I just put my hands on the palm rest, the tray often starts to slide inward. I could think of something to fix it, but that would make shoving it back under the table pointless.