Looking for a tool to help read atmospheric pressure? Check out this aneroid barometer. It reads in units of mmHg or hPa (hectopascal), can be hung on the wall using a small nail or mounted using the clear plastic retaining ring (included). The barometer is silver with black markings and the face has a diameter of 3.5". A small screwdriver is provided to calibrate the barometer along with an operating instruction guide.