AAAA batteries, sometimes called Quadruple A batteries, are small cylindrical batteries. These batteries are sometimes referred to as LR8D425 or 25A models. Compared to an AAA battery, AAAA batteries are 40% smaller and 20% thinner, with a length of 42.5 mm and 8.3 mm in diameter. They have a power rating of 1.5 volts.
AAAA batteries are typically used in small devices such as LED penlights, laser pointers, powered computer styluses and miniature headphone amplifiers. Due to their limited history of being used in consumer electronics, they are not used in as many devices as AA or AAA batteries and are not as widely available.