I would really advise against the masta body suit. I bought one for my boy. Bought the size I was advised to by the retailer, then put it on my boy and it fitted fine. The next morning it had grown by about 5ft and was dragging along the floor behind him, the belly band had slipped over his 'bits' causing a lovely smelly mess and most of the stitching around the rest of the rug had come undone. I took it back to the retailers who sent it back to masta, and all I was told by masta was that I had bought the wrong size (not my fault, only bought the size I was told to, and the retailers know my horse) so would not do any thing about it.
I have now got a Dress Circle suit which is much better. No problems at all.