I bought this to use as a keyboard tray. I mounted them flat on the bottom of the shelf I was using and then attached the other side to the table (the table has 3 tiers and I attached the shelf and rails to the bottom one. I've done this before with a regular set). of slides and I broke them once while leaning against the shelf. I'm not worried if these slides will do it. Now every day I lean against the shelf and am sure that the shelf itself will break before the slides. great product