The Model 637 Pro Series is the Performance Center-enhanced version of the exposed-hammer aluminum J-frame, providing a factory-improved trigger and chamfered cylinder for competitive shooters and serious carry users. The Pro trigger brings a cleaner break to the exposed-hammer Airweight, making single-action accuracy work more practical in range contexts. Type: Revolver Action: Double-Action Caliber: .38 Special Capacity: 5 Year introduced: 2010, USA Weight: 15 oz Overall length: 6.31" Status: Active Intended use: Concealed Carry, Backup