Great, little device to solve a common problem with this storage system. Fits perfectly in the rails. I’m going to try just using one side—it should be sufficient to still stop the bins. Printed a bunch of them. I had a 0.2 nozzle in, though, so it took a while! I installed them in from the end of the rails a bit so the bins stop flush with the front. And you can flip it to act as a stopper for a shelf.