Bests & Worsts Reviews from Amazon

This balance board is very solid and very well made. It's 17.5 in x 13.5. The rocker part on the bottom does NOT go to the edges ( about 3 inches in on the 17 inch side and 2 inches in on the 13 inch side). When you put this on the ground, it can stand by itself. It has two rockers on the bottom which are joined by a solid piece of wood. This is heavy duty and weighs 5lbs. You can turn it around (You stand with feet so that heels are near the shorter side) to rock/wobble/balance backwards and forwards vs side to side (stand with heels inside the longer side) . If you've been to PT, you know what I am talking about. So this board can wobble side-to-side and backwards and forwards. Looking at some of the reviews, I want to add a few words: If you have good balance, this will probably be too easy for you. But if you have poor balance or want to improve your balance, this is a SAFE device. I have tried some of the round wobble boards with the single (curved) ball on the bottom and they present a challenge which is great but when you have poor balance, you don't want to break your neck trying to improve it! This board is sturdy and feels very safe. I put it on thin type carpet and I have had zero slippage. The top is covered with a material that resembles the heavy duty sandpaper grit. It's great for me. It's not the cheapest on this site and I wasn't looking for cheap. I wanted safe. Edited to add 4/19 I have central vertigo and I've made tremendous improvements in my balance after 4 months of using this daily. I watched the company video and am now working on turning my head and then turning my head and shoulders while balancing. Those are the next big steps. The rocker board is by its design less unstable than a board with just one ball (wobble board). This wooden rocker board just gives you one plane of instability at a time. It does not have a 360 degree rotation which is far more challenging. Some sites say that a rocker board (such as the one I'm reviewing) is for beginners. Whatever. Bottom line: I'm not breaking my neck and I'm improving my balance. I love this thing!!