Glock 18C: Selective-fire variant of the Glock 17, developed at the request of the Austrian counter-terrorist unit EKO Cobra. The Glock 18 is not available to the civilian market. This machine pistol-class firearm has a lever-type fire-control selector switch, installed on the left side of the slide, in the rear, serrated portion (selector lever in the in the bottom position – continuous fire, top setting – single fire). The firearm is typically used with an extended 33-round capacity magazine. Early Glock 18’s were ported to reduce muzzle rise during automatic fire. Another compensated variant was also produced, known as the Glock 18C. It has a keyhole opening cut into the forward portion of the slide, not unlike the opening on the Glock long-slide models, although the G18 has a standard-length slide. The keyhole opening provides a venting area to allow the four, progressively-larger (from back to front) compensator cuts machined into the barrel to accomplish their job, which is to afford more control over the rapid-firing machine pistol. The compensator cuts, of varying widths start about halfway back on the top. The rear two cuts are narrow, while the front two cuts are wider. The slide is also hollowed, or dished-out in a rectangular pattern between the rear of the ejection port and the rear sight. The pistol’s rate of fire in fully automatic mode is approx. 1100-1200 rounds/min. Most of the other characteristics are similar to the Glock 17.