The Radial Engine Piston Desk Clock (Metallic Edition) was created using a 1940's radial engine piston called the WWII Jacobs R-755. The piston was used to power airplanes including the Beechcraft Staggerwing, Boeing Stearman 75, and Avro Anson. The piston measures 5" in diameter and 3" in height. The clock face measures 3 1/2" in diameter. It is made in the USA and has been machined at a 70-degree angle for excellent viewing. It is also satin polished, and clear-coated. The clock requires one AA battery.