Last summer I picked up a used Gaiam ball at a thrift shop. (I think it was this one: Gaiam Balance Ball Beginner Kit (Small, Purple)) Unfortunately, I think it had a history of over-inflation or was just worn-out, so inflating it to the correct size left it kind of flat, and I doubt it’s safe to use anymore, even though it’s not leaking. So recently I ordered a cheap Reehut Anti-Burst Core Exercise Ball w/ Pump & Manual for Yoga, Workout, Fitness (Grey, 55cm) from Amazon, but when it arrived with a hole in it, I sent it back and opted to fork over the extra money for a Black Mountain Products ball. I’m glad that I did. When I took it out of the package, my first reaction was “Wow! This thing is heavy!” Unfortunately I did not think to weigh the ball before inflating it. The rubber is much thicker than either the Gaiam ball or the Rehut ball--something impossible to determine from product photos on the Internet! It came in a box with a small plastic foot pump, 2 air hole pins, and some really great, detailed instructions for how to inflate the ball (including circumference measurements as well as the standard diameter measure, both of which are in centimeters and inches) and notes on how to decrease your chances of puncturing the ball in use. The inflation instructions are explicit about only using the pump included because it won’t allow you to over-inflate the ball. I didn’t do that. Instead I used a multi-purpose plunger-type pump with the tapered inflation nozzle from this MINTCRAFT FDQ910 1 1 1 Inflation Kit, 4-Piece to inflate the ball. As the ball got close to the correct size, I measured the circumference with a tape measure every few pumps, being very careful not to over-inflate it. The directions are also correct in saying that the ball will feel full before it actually reaches the correct/stated size. If you think your ball is mis-marked/smaller than stated, measure it to check, then keep pumping. Seriously. This ball seemed fully inflated at 48 cm tall (150 cm around), but I kept pumping and it eventually reached 55 cm tall (172 cm around). When I was done, the ball was very firm, with just a little give when I sat on it. That’s a *good* thing. Rubber stretches over time, and I don’t want my ball being super soft and squishy/not even ball shaped when inflated to 55 cm anytime soon!Since I didn’t use the included plastic foot pump, I can’t be certain of it’s quality, but it seems pretty cheap/flimsy. Honestly, I find it weird that pumps are included with exercise balls in the first place. I’d rather my exercise ball be a dollar or two cheaper and buy a better, multi-purpose pump separately. One thing I do want to note about the pump, however, is that the hose can be attached to one of two valves on the side of it. The blue one is for inflating the ball, and the red is for deflating the ball, so if you do use the included pump, make sure you’ve put the hose on the right valve, or you could be wasting your time.Because the ball is basically smooth on the outside, it might slip out of your hands if they get particularly sweaty. Since most exercise ball activities involve balancing on the ball, rather than holding it, however, I consider that a pretty minor negative. The smoothness also allows you to sort of see your reflection, which you may or may not find distracting.The ball appears to have a slight seam/mold line in the rubber around the middle.Because of the weight of the high-quality thick rubber, certain exercises that involve holding or lifting the ball may cause you to fatigue a little quicker. In the long run, this will also be a positive, as it will build a touch more strength, but if you’re incredibly weak, you may want to consider a different ball or a different form of exercise altogether.It's worth noting that the ball is made in China, for anyone who is a stickler about avoiding Chinese-made products or strictly buying U.S.-made ones. I'll take my products from just about anywhere, as long as they're decent quality.There were a couple of spots on the ball that seemed kind of dirty when I first opened it. While I suppose that it’s possible I could have received a used ball, I doubt it. I’m betting that it’s just a little bit of residue or something from the factory. Anyway, it pretty much came off when I went at it with a cheap melamine sponge. Beyond that, there are a few minor surface imperfections and the wrinkles/creases from its previous life folded up in a box are still smoothing out, but that’s to be expected.Overall I’m pleased with the purchase and would highly recommend it. The ball itself seems to be much higher quality than any other exercise ball I have experience with. Since I don’t mind the minor negatives, I still consider this a 5-star product. If I ever have any problems with it, I will update my review and include info on interactions with BMP customer service and all that jazz.