A Powerlet cartridge is a small disposable metal container holding 12 gram (0.423287545261344 oz) of liquid CO₂

Carbon dioxide

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 and often a small quantity of oil, used as a power source for certain air gun

Air gun

An air gun is a rifle , pistol , or shotgun that fires projectiles by means of compressed air or other gas, in contrast to a firearm, which burns a propellant. Most air guns use metallic projectiles as ammunition. Air guns that only use plastic projectiles are classified as airsoft...

s, paintball marker

Paintball marker

A paintball marker, also known as a paintball gun, is the main piece of equipment in the sport of paintball. Markers use an expanding gas, such as carbon dioxide or compressed air, to propel paintballs through the barrel. Some paintball players refer to the piece of equipment as a "marker" rather...

s, and a few airsoft guns. Originally developed and the trademark owned by Crosman Corporation and introduced to the market in 1954, the Powerlet cartridge has become the dominant source of power for inexpensive, rapid fire air guns from many manufacturers.
The Powerlet container typically lasts between 20 and 40 shots depending on the gun and environmental conditions. You normally get about 10 average shots from a new bottle, then every shot after that becomes less powerful. For paintball markers, you can expect around 20-40 shots because of the increased weight of the paintball compared to an airgun projectile.

Today, for paintball markers, this technology is considered out dated. However, some still use of Powerlet cartridges for stock paintball

Stock paintball

Stockclass paintball is a paintball game variant, in which players are restricted to use the most basic paintball markers to tag opponents with.-The rules:Stock paintball players must adhere to the following rules, in regards to usable paintball markers....

, because they cannot fire as many shots as a modern

Carbon dioxide

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

tank can. They are also still favoured for paintball pistols, and players wishing to run 'light', and offer considerable weight savings over a modern High Pressure Air tank.