Pre-charged pneumatic (PCP) air guns are usually filled by decanting from an air reservoir, such as a diving cylinder or by charging directly with a stirrup pump. Because of the need for cylinders or charging systems, PCP guns have higher initial costs but much lower operating costs when compared to CO2 guns. PCP guns have very low recoil and can fire many shots per charge. PCP guns are very popular in the UK and Europe because of their accuracy and ease of use. They are widely used in the sport of Field Target shooting as well as hunting, and are usually fitted with telescopic sights.