"Before getting the Sherpa carriers, my cats would be transported in hard plastic carriers. While I was carrying them, they would slide all over the place, even with a towel on the bottom of the carrier. The soft sided Sherpas are much more friendly and cause them less discomfort. They never like going to the vet, but these carriers seem to make them a bit more comfortable. I have two large ones and one medium now and will not go back to the plastic ones."