Instruct: Classify Amazon reviews into positive or negative sentiment
Query: became so flat so fast.

The first 2 days this worked okay ... took pressure off my spine. But the next few days it became so flat. and didn't even have any fluff to it. its not worth the $... then again you do get what you paid for. so i wouldn't buy this if your sitting for long period of time. i guess if you sit for a few min at a time this is great for you.