1. Best part is battery backup, but manufacturing defect products. 2. Oneside speaker was broken (opened) when it was delivered. 3. After I checked everything, I decided to accept this product. 4. Left side speaker was stop working on 20th day and also the other one stop working on 30th day. 5. I only compromised to accept this for it's battery backup. 6. But I was wrong and it's prooved. Now I have no choice. 7. Company should take more care of its manufacturing part.