RV LED Black Triple Tank Water Level Indicator Customise this kit to your needs with a Triple tank gauge and a sender probe spanning 2.5 m, 5 m, or 7.5 m! Push a button to monitor your three tanks - no 12V wiring needed! The indicator gauge has a replaceable battery for easy use. The water gauge measures only H65mm x W65mm x D16mm so it is small enough to fit any application Suitable for Plastic and Metal Tanks. Easy Installation. Fits Existing Water Tanks Battery Included Suitable for Caravans, Boats & Camper Trailers. 3 x RV Tank Sender Probes Required. This easy to fit tank sender probe only requires one 22mm (7/8") hole in the side of the tank and suits tanks from 100mm to 280mm (4" to10") deep. The sender probe is sealed by a special grommet which is compressed in the hole when the nut is tightened and measures the water level by contact with the 5 sensors along the arm. It has no moving parts.