Czechoslovakia (currently, the Czech Republic) began searching for a dependable submachinegun (SMG) for its infantry and non-infantry military personnel shortly after the conclusion of World War II. The CZ Model 25 produced in the late 1940s is the best known in a series of CZ models (alternately known as the Sa. 23, Sa. 24, Sa. 25 and Sa. 26) produced by Czech arms designer Vaclav Holek at the Uhersky Brod arms factory.

The Sa. 23 featured a blowback action with an unlocked breech, fired from the open-bolt position. Rate of fire was determined by the degree of pressure applied to the trigger by the operator. Light pressure resulted in single- or short-burst fire; constant trigger pressure resulted in a fully automatic mode of fire.

The series features a telescoping bolt in which the forward part of the moving bolt extends past the back of the barrel and wraps around it. This helped improve the weapon's balance and handling. A vertical handgrip (nearly) centered on the weapon's 445-mm or 17.5-inch length (on the folding stock model) that housed the magazine and trigger mechanism also served to improve handling for the Sa. 23 series.

Folding stock models (Sa. 25 and Sa. 26) tipped the scale at approximately 3.27 kilograms (7 pounds) empty; fixed wood stock models (Sa. 23 and Sa. 24) weighed 3.5 kilograms (7.7 pounds) empty. The folding stock model (Sa. 25 and Sa. 26) folded was 445 mm (17.5 inches); the fixed stock and unfolded, folding stock models were 686 mm (27 inches) in length. Sa. 23 series barrel length was 284 mm or 11.18 inches.

A pair of cartridges were used in the Sa. 23 series SMG: the Russian 7.62x25mm and the 9x19mm Luger/Parabellum. Feed systems for the Sa. 23 were 24- or 40-round (9mm) and 32 rounds for the 7.62. Rate of fire for the series was 650 rounds per minute, and the Sa. 23 series had an effective range of 100 to 200 meters (328 feet to 656 feet).

7.62 and 9mm models can be identified by magazine position: Forward sloping mags are loaded with Russian 7.62; 9mm models feature a vertical magazine position.