Maximize the performance and longevity of Trojan deep-cycle batteries with automatic water refilling through the automatic water filling system. Designed for Trojan Pegasus 6v, 8v, and 12v flooded batteries, HydroLink takes the guesswork out of filling water; once installed, a full set of batteries can be filled to standard water levels in less than 30 seconds , so as to reduce the possibility of shortening the battery life due to excessive addition of water.