This switch indicates battery amperage, thus making you aware of your battery level and a possible bad day on the water. WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov Economical Quickly tests the current charge of two separate batteries Constructed of corrosion resistant stamped anodized aluminum Clear gauge shows current charge status of each battery by toggling the 3-position rocker switch between the two Dimensions: 2-1/2"H x 3-1/4"W