Look up: AA battery

1. 
   AA battery
   An `AA battery` ( or ) is a dry cell-type battery commonly used in portable electronic devices. An AA battery measures 51mm in length (50.1mm without the button terminal), 13.5-14.5mm in diameter, and generally weighs (depending upon materials) approximately 23g (1.97Ɨ0.56 inches and 0.81 ounces). The AA battery type was standardized by ANSI in 1947 and is known internationally as `LR6` (alkaline) or `R6` (carbon-zinc) or `Mignon.` As an AA bat...
   Found on http://en.wikipedia.org/wiki/AA_battery
   
   
2. 
   AAA battery
   An `AAA` battery (pronounced `triple A`) is 44.5 mm long and 10.5 mm in diameter, weighing around 11.5 grams. Output of alkaline batteries in this size is 1.5 volts, 900 to 1,155 mAĆ·h (3240 to 4158 coulombs). Modern nickel metal hydride (NiMH) batteries of this size can store up to about 1000 mAh, with an output of 1.2 volts. The battery is also classified as `LR03` (IEC), `24A` (ANSI/NEDA), `R03`, `MN2400`, `AM4`, `UM4`, `HP16`, ...
   Found on http://en.wikipedia.org/wiki/AAA_battery
   
   
3. 
   AAAA battery
   An `AAAA` battery is 42.5 mm long and 8.3 mm in diameter, weighing around 6.5 grams. Output of alkaline batteries in this size is 1.5 volts, 625 mAĆ·h. This battery is also classified as `LR8D425` (IEC) and `25A` (ANSI/NEDA). The battery is also known by its Duracell type number `MN2500` or `MX2500` and Energizer type number `E96`. This battery size is most often used in devices requiring small batteries such as laser pointers, LED penlights, po...
   Found on http://en.wikipedia.org/wiki/AAAA_batter