The Smith & Wesson 637 is a small-frame five-shot revolver. It features an aluminum alloy frame stainless steel cylinder and barrel and three styles of external hammer. This pistol also offers integral front and fixed rear sights black synthetic grips and rating for continuous P use. The Enhanced Action model sports custom wood grips. The older Smith Wesson 637 has a black blade front sight and full-length extractor.DetailsAction SADA - Caliber .38 SW Special P - Capacity 5 - Finish Stainless - Material Aluminum Alloy Steel - Grips Black Synthetic - Sights Integral Fixed - Barrel Length 1.875 - Overall Length 6.31 - Weight 14.3 oz - The Smith Wesson J-Frame has become the most popular small frame personal defense revolver on the market. With decades of reliable performance to its credit the J-frame line offers models capable of firing .22 LR .22 Magnum .38 SW Special and the more powerful .357 Magnum loads. Smith Wesson offers these revolvers from our production MP Pro Series and Classics lines in three diverse hammer designs internal exposed and shrouded.