Ambient Weather 1605B-45 Fischer Solid Brass Nautical Open Face Barometer, 6-5/8" The USA version of this instrument displays the metric units (mbar) on the inner scale and imperial units (inHg) on the outer scale (opposite of the image). This beautiful nautical instrument is made from the finest materials, and is at home with any marine decor. The open face barometer is equipped with a bayonet lock in the housing, so the barometric pressure can be easily calibrated. The back includes a hook for easy hanging. Operates to about 3,000 feet altitude (do not order if you live above 3,000 feet).