This is an example of a experimental double action prototype revolver produced by Colt. The accompanying factory letter dated, December 18, 2008, confirms the serial number, caliber, the 4 inch long aluminum alloy barrel left in the white with the remaining surfaces receiving a blue and anodized finish, aluminum alloy D-frame, and side plate and banded barrel of steel, without being furnished with grips (currently fitted with checkered plastic Coltwood grips with embossed Rampant Colt at the top). The letter also confirms that the revolver was an experimental prototype with low serial number kept by the Colt factory with the included tag attached to the trigger guard marked "#37LW" and "Replace with alum barrel". Matching serial number on frame and crane and a Rampant Colt stamped on the left side of the frame are the only markings on the revolver. Blade front sight and frame notch rear sight. Included is circa 1950s brown Colt hinge lid box.