It is a sad thing to say about any product, but I really feel this one is not suitable for purpose and should probably be withdrawn from the market until more research and development is put in to making it suitable for the purpose for which it is intended.
I say this as a reasonably experienced Pilates teacher, who has been using various different manufacturers equipment in class for the last six years. In that time I have had a few items fail, but in general by sticking to recommended names this has been a rare occurrence. However, this year, wanting to replace my classes stock of small inflated exercise balls for slightly larger ones that would allow for a greater exercise range, I looked around and found this one, which was labeled similarly to a number I had seen in certain gyms where I teach class.
I am sorry to report that of the 28 I have purchased since January this year no less than 10 have failed in class, a failure rate unprecedented in any of the other manufacturers I have purchase similar items from in the past. In fact only a couple of days ago simply leaning my upper body on one way enough to cause it to burst in front of a class.
The remaining balls are now sitting in a bag (hopefully they can be recycled) whilst I have returned to the older ones I still possess, which are still in good condition if a little faded. In the meantime I am looking at possible replacements for my classes and trialing a different manufacturer.
In the meantime I can only regretfully suggest that if anyone is looking for equipment to use for a similar purpose to the one I intended they seriously consider another product.