Bests & Worsts Reviews from Amazon

As soon as I inflated the ball, I immediately noticed that it was much smaller than the 65cm size which I ordered. Although "65cm" is printed on the ball, this is clearly not the case (see the pic). <Added on Jan 12, 2016> Thanks to the comments from some of you, I figured that the problem was lack of instruction. This was my first ball and how would I have known that it had to be stretched over a time if there's no instruction provided with the product? It was a nice looking ball with a reasonable price.