Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: DONT BUY THIS PUMP

When I went back to work, I used the Avent ISIS pump and have had great success w/ it. One day, I forgot to bring my pump to work and since I live pretty far away decided to run to the store and pick up something as a spare. What a disappointment!!I wish I had just gone ahead and spent the extra $15 and got another ISIS. Nothing is good about this pump. It leaks, it's incredibly inefficient (I usually get 3-4 oz and got only a 1 oz in the same amount of time and felt like I had carpal tunnel),it's easy to overpump and it makes this annoying noise.Stay away from this thing!!