The most famous of Henry Deringer's products, an estimated 15,000 were produced between the Mexican War through the Civil War, usually in pairs. Popularity of the pistol is attested in large number of imitations and nickname "Derringer" applied to them, even when clearly not Deringer's products. Prices can fluctuate widely based on agent marks occasionally found on barrel. Care is advised in purchasing purported "true" derringers. Beware of fakes! Deringer Percussion Pocket Pistols Caliber varied, usually .41 or larger. They were usually sold in pairs, and a cased pair will bring a premium. Collectors divide these into three sizes – Small Pocket Size with 1 ½” to 3” barrels (the very smallest ones will bring a slight premium), no ramrods. Medium Pocket Size with 3 ½” to 6” barrels. Larger ones have ramrods. Duelling Size with 7” to 9” barrels, with ramrods. Rare, worth premium.