Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Great chair for the office!

I'm an accountant and I sit ALL DAY! So, what better way to get in some core training than with a balance ball chair. When I initially pumped up the ball it was small and I mean very small. I let the chair sit over the weekend with as much air as I could force into it. On Monday I added a lot more air and it was just about right. Today, Tuesday I added a bit more and I cannot be more pleased. As others have said it really seems as if the ball is too small for the chair. Give it a day or two to rest, add more air and you will be amazed. Fully inflated and sitting, the balance ball touches the back of the chair as well as the front metal retainer. I bought the black chair and have not had any issues with inflation. Remember, if the concept of sitting on a balance ball for 8 hours is new to you, BEWARE! You WILL have back pain for the first few days! However, that is your body becoming stronger. Cheers to better health!