Bought this for my Nokia 6230. This battery works just great and it is original. As one reviewer had said before, one can check the authencity of the battery by entering the serial number in Nokia's site. My phone, which was dying with the old battery, has now got a fresh lease of life. The battery usually lasts for about 2 - 3 days for me (around 5 to 6 hours of talk time). This battery has higher mAh (more battery power) than the same Nokia BL-5C sold in other countries. Pleased with the battery life. I think the negative reviews may be from people who bought cheap counterfeit batteries from sellers in Amazon Marketplace.