Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Poor Product

This device has two major flaws, both of which alone would render it useless. First, it simply does not pump well. One has to work a lot and there is almost no result. Second the stopper breaks after a couple of uses. There are three rubber rings around the stopper that are meant to keep a tight fit with the bottle. However, these rings break off after a couple of uses, and the stopper does not work any more. Simply a poorly designed product.