Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Not for all Kettrike bikes... be careful

I purchased the Kettrike Air Happy bike and in the Amazon.com website, they state that the Kettrike Tandem Insert is an accesory of this bike. It is not. Even in the Manufacture's Information it states that it can be used with an adjustable Kettrike frame, one that separates in two. Well the Air Happy Kettrike separates in two and it does not fit. I'm sure, having the correct bike would make this item a 5 star toy. I guess not being able to return it because my 30 days are up has soured the situation. Good luck and be sure you purchase the correct bike.