Great Purchase. I went back and forth between this and a wooden box. Watched a lot of youtube reviews and did a lot of searching. I kept coming back to this box. I'm new to box jumps, so decided a foam box would be best. I'm 5'4" woman and figured 20 inches would be a good start and then can move to 24 and 30. Which is why I chose the 20x24x30 size. My sons 5-10 180 lb, can do the 30 right away. I will get there! The box was very stable on all 3 sizes. And a good landing surface. I use it on a fitness mat on carpet. Doesn't slide. Overall I am very happy with this purchase. I really wanted this one after looking at several other models. It sold out while I was deciding, but I kept checking back and thankfully it was available again. I also found a few videos showing exercises and stretches you can do using the box. This foam box is a great purchase!