Instruct: Classify Amazon reviews into positive or negative sentiment
Query: be prepared to return it

Initially, I bought one of these and it seemed to be working ok for 1-2 days, so I bought two more. Surprisingly, after 3-4 days, one of them stopped working -- it stayed permanently on, which pretty much defeats the purpose of having a motion detecting unit. I exchanged it, and a second one has stopped working about 3-4 days -- it also stayed permanently on.So far, 2/4 have been defective. This is either poor quality control or poor engineering.Not recommended..