Contains 1 piece CR2045 3v coin battery.Fit for bmw key fob. Easy to install Re-programming of key fob is not required Each item measures 20mm(about 0.78 inch) in diameter by 3.2mm(about 0.12 inch) thickness. Notice: please make sure CR2045 is the battery model you need before purchasing. This item isn't a remote key, it's just a remote key shell. NO interior (remote/electronics/transponder chips) unit inside Pls kindly check out your key blade and button position before buying, make sure your remote key case looks exactly the same with this case Best replacement for broken or worn keys, or great for an additional key Constructed with high quality materials for long lasting durability