These small revolvers were designed to fire a full power round and are as simple and easy to use as they are reliable. Available in various calibers and with three diverse hammer designs" it is no surprise that the Smith & Wesson J-Frame has become the most popular" small-frame" defense revolver on the market. The Model 642 is a variation of the Model 42 Centennial Airweight that integrates the time-tested features of the original with modern advancements. This lightweight" enclosed hammer revolver is a favorite back-up and concealed carry firearm.