The old cache battery took the server down because of cache write fault. We ordered a replacement. It arrived quickly and worked as expected. I understood the specifications of this battery by its description. The installation was easy and our server powered on with no issue. I will order from them again. The most common RAID card in the DL380 G9, the P440AR controller, uses the 815983-001 battery but the part has been replaced by 878643-001. Either or will work on your server.