The Panasonic 2CR5 6V Lithium battery is used in a variety of cameras, including the Contax 645. It is also used in some point-and-shoots, including some Canon SureShots.
You should always reference both a camera manual and a battery list when buying a battery for a new (or new-to-you) camera. It is not unusual for different generations of similar cameras to use different batteries.
Some older camera manuals will list obsolete battery names and some differ across battery brands. This is a replacement for: 2CR5M, 5032LC, DL245, EL2CR5, KL2CR5, RL2CR5. That is not an exhaustive list.