CR123 batteries are specialized Lithium-ion disposable (primary) 3 Volt batteries. (They use manganese dioxide, MnO2, as their primary cathode material.) Their small size makes them perfect for digital and film photography (cameras and flash units), high-lumen flashlights, and other portable electronic equipment. These lithium batteries are not interchangeable with zinc chemistries.
Common names for the CR123A include: Panasonic, CR123A, Energizer EL123AP, Duracell Ultra DL123, Sony CR123A, Varta CR123A, Maxell CR123, Camera Battery, 2/3A, 123, 17345, 16340, CR-123A, 6135-99-851-1379, CR17345, 5018LC, 123A, CR123A, SF123, PL123, EL123, KL123, LR123, VL123, RL123, RL123A, SF12-BB, K123A, RCR-123A, 23-155, CR-123APA, DL2/3A, K123LA, PR123, ULCR123R, one two three A, Grainger 11W123
A rechargeable lithium-polymer (LiPo) battery is available - usually it will start off with the prefix BR as in BR2/3A or BR123A.
Typical capacity for a disposable lithium cell is 1500 mAh and for a rechargeable LiPo cell is 700mAh. Voltage is 3V for disposable and 3.6V for LiPo. The dimensions are 34.5 mm Height and 17 mm in diameter. Shelf life is typically 8-10 years.