The polished brass porthole barometer measures 5.5"Dia. This item features a brass precision barometer in a solid brass tarnish proof porthole case. It's movements are calibrated for altitudes to 3500' above sea level. It will add a definite nautical touch to whatever room it is placed in and is a must have for those who appreciate high quality nautical decor. It makes a great gift and impressive decoration. It will accurately and precisely predict weather conditions coming to your area.