Digital pressure gauges for partial pressure blending are highly accurate and quite expensive. Most types are battery powered. During the offseason, if batteries are not removed, they can rupture and leak acid into the gauge thereby destroying it. This can be a very expensive lesson. Global's digital mixing gauge #45305OX can now be purchased with an external battery pack option (2 AAA batteries) which keeps the batteries away from the sensitive electronics of the digital gauge. Option only, does not include gauge.