H-B DURAC Glass Weather Ball Barometer; 152mm Diameter (B61501-0000) DURAC glass weather ball barometer Diameter: 152mm (6in); construction: glass Enables you to predict weather conditions; rising water in the tube means bad weather, falling water in the tube means good weather Accuracy: 3.5mbar; 0.1inHg; 0.3cm Hg.