The CZ 75 is a double-action semi-automatic handgun produced in the Czech Republic / Czechoslovakia. First produced in 1975, the CZ 75 quickly gained a reputation for reliability and excellent ergonomics as well as the unusual feature of having the slide run along the inside of the frame (similar to the SIG P210). The CZ 75 has undergone a series of changes throughout it's history, resulting in a number of variants:
The "First Model" or "Short-railed" CZ 75, distinguishable by its shorter slide rails, rounded triggerguard, and horn hammer (produced from 1975 to 1979).
The "Pre-B" CZ 75 intended for export, identifiable by its full-length slide rails, rounded triggerguard, and horn hammer.
The CZ 75B, which is the current production model (first produced in 1993) and features an internal firing pin block (visible as a small hole in the slide just above the safety switch) and full-length slide rails. Most also have a no-reflection ridge along the top of the slide, a ring hammer, and a two-handed tiggerguard. Note that a few "Pre-B" CZ 75s have all of these features, but lack the firing pin block that differentiates the B series.
The CZ 75BD, same as the CZ 75B but with a decock lever in place of the safety switch.
The CZ 75SAO, Single-action only variant, notable by its match (straight) trigger, beavertail tang and enlarged safety switch.
The CZ 75 Compact with a shorter (3.8 inch) barrel, railed dustcover, and beavertail tang. These were introduced in 1993 during the transitional period when the CZ 75B began replacing the Pre-B model. As such, some CZ 75 Compacts do not possess the firing pin safety of the "B" models.
The CZ 85B, a CZ 75B with the safety and slidelock controls replicated on the right side of the frame for left-handed use.
The CZ 75 Automatic, a CZ 75 with full-auto fire capability. Distinguishable by the extended muzzle break and magazine-foregrip attachment.