I used the model xxx to clean today and I was worried it would scratch the hardwood floors. So, I didn't want to take the sled look away by adding wheels, so what I did was, I cut some clear tubing and slipped it on both sleds (the cut on top)and it won't scratch the floor. It slides great on the rug and the hardwood floor there is some resistance but manageable when pulling it and it won't go flying across the floor and scratch it. I used the aquarium tubing and it has a sticky consistency so it stays on the sled. Looking at it, you can't even see the tubing.