After purchasing my 4 year old Casita I found that the right side rail was already broken. These replacement parts are perfect for the originals. I just drilled an extra hole to allow two screws to be used. Just like Casita originally did. Raise the drawer a little and further reduce wear on the guides. Also, it allows you to catch BETTER INTERACTION. I also bought some small PTFE corner strips from McMaster-Carr. I mounted them under the drawer slides. Now the box stays securely closed. Now it should not extend on the road and when braking, as if it were fully extended, should not put pressure on this interchangeable guide.