The Petri .38 Airweight Revolver is snubnosed revolver is chambered for .38 Special ammunition, has a five-shot cylinder capacity, and can fire FMJ, Dum-Dum, incendiary, cyanide-tipped and High Explosive bullets (the last two types are fictitious). It is described as Cate Archer's signature weapon, but many low-level H.A.R.M. thugs use it as well. Being a revolver, it cannot be fitted with a sound suppressor. Despite the very short barrel, this "purse gun" boasts a higher damage-per-bullet ratio ingame than the 9x19mm handguns have, especially when loaded with FMJ or cyanide-tipped ammunition, as the former needs fewer hits than the 9x19mm handguns do to kill an opponent and the latter has a good chance of killing an opponent outright in one hit.
Smith & Wesson Model 37 Airweight on Wikipedia