The Model 637 Airweight Chief Special is the aluminum-frame J-frame with an external exposed hammer spur, allowing single-action cocking for deliberate precision shots while retaining the lightweight aluminum frame of the Airweight series. The stainless steel cylinder paired with the aluminum frame provides a practical corrosion-resistant combination. A companion to the hammerless 642 for those who want single-action capability. Type: Revolver Action: Double-Action Caliber: .38 Special Capacity: 5 Year introduced: 1990, USA Weight: 15 oz Overall length: 6.31" Status: Active Intended use: Concealed Carry, Backup