The majority of paintball markers have four main components: body, a hooper, a gas system (air tank), and a barrel. There is, however, a strong following of stock-class players who use markers with a purposely low rate fire and capacity. Stock class markers are usually pump-action and powered by a 12 gram CO2 powerlets. Marker construction varies widely, from ultra-economy models not seriously made for the sport, to multi-thousand dollar electronic markers with custom graphics and body milling.