The Uzi carbine is similar in appearance to the Uzi submachine gun. The Uzi carbine is fitted with a 400-mm (16-inch) barrel, to meet the minimum rifle barrel length requirement for civilian sales in the United States. A small number of Uzi carbines were produced with the standard length barrel for special markets. It fires from a closed-bolt position in semi-automatic mode only and uses a floating firing pin as opposed to a fixed firing pin. The FS-style selector switch has two positions (the automatic setting was blocked): "F" for "fire" (semi-auto) and "S" for "safe". Uzi carbines are available in calibers .22LR, 9mm, .41 AE, and .45 ACP.