Instruct: Classify a given review into positive or negative sentiment.
Query: Not the best case

I bought this as an amazon recommendation but have found it to cause build-up of static electricity, causing the mp3 player to skip. For instance, the silicone can build-up static on the fabric of your car seat or the lining of a jacket pocket, so much so that tapping on the back or flicking the cover will cause an audible skip, just like a CD player. I found the most difficulty waiting on a train in Chicago, where electricty is high, but once I removed the silicone case the skipping stopped. Look for another, more protective case.