Powder testers or "eprouvettes" were used to test the quality of gunpowder. This example is based on a boxlock pocket pistol design but instead of a normal barrel a cover fits against the muzzle. When the powder is ignited, this plate is forced forward and locks in place on the teeth of the wheel allowing the user to figure out how much pressure was generated. This tester is particularly ornate and is engraved with floral patterns and fitted with a nicely checkered and carved grip.