The iSeries Tank Systems Monitor provides hassle free tank monitoring for your RV or boat. The iSeries is patented technology with Level Alert. It is the ONLY tank monitor tested and approved by the United States Coast Guard. It is NMMA Certified using ABYC(R) standards. Sensors on the iSeries system mount externally and actually read through the tank wall. It is perfect for new projects or for replacing your old tank monitoring system.