I used the rails as the bottom laptop tray mount and they worked great. was surprised by their good quality and solid construction. I really liked that the slides were an inch longer than the 14" they were designed for, without the extra extension they would not have been suitable for my use. They are very solidly built and roll quite easily. The delivery was excellent and there were no problems with the payment either. I would recommend these films and the dealer. I only have a few pounds. weight on them and they work great with the bottom mount. As strong as they are, I wouldn't be afraid to put a nominal 100 pounds on them when side mounted. You can't beat them for money. They are just as high quality as the more expensive slides. They also have rubber bumpers on the back that seem to keep the clasp closed.