The OTs-21 Malysh (Russian: ОЦ-21 «Малыш», meaning "kid") is a 9 mm semi-automatic pistol designed by the KBP Instrument Design Bureau for special applications where concealment is a key priority. The Malysh operates on the simple blowback principle; it is a double action only design with the ammunition capacity limited to five 9×18mm Makarov rounds (can use only 57-N-181S cartridges) in a box magazine with a base extension for more comfortable holding and firing. It features an internal hammer and there are no protrusions to hinder rapid withdrawal from a pocket or holster. The pistol has no safety other than the need for a definite pressure on the trigger. There are also no sights other than a groove along the top of the slide, emphasizing the intention that the OTs-21 Malysh is limited