I have a desk where the ball bearings of the original pencil case fell out. It fit perfectly. It doesn't extend very far and the mechanism is far from smooth, but it gets the job done and fixes the problem. I just reused existing wood screws and machine screws. You can't separate the slide/slide parts, but the drawer in my case simply attaches to the rails with two mounting screws from the inside of the drawer. So you first attach the rail to the frame and then attach the screws from my box to the rail in my case. If your drawer isn't attached this way, installation can be tricky - drill holes in your drawer to match the slides and purchase mounting screws as mounting screws are not included.