Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Quality is not there

I have a friend who purchased a cushion like this from another store. It felt great to sit on and relieved my coccyx pressure completely and immediately. My cushion flattens completely. I am not heavy, however, it does not retain any of it's shape when I sit on it. It's therefore useless in giving me any coccyx relief. I don't know if mine was not of the same quality as others, but it is useless to me. I am very disappointed. I was so hopeful!