Tuflong Batteries is fully sealed maintenance free It’s covered with a double lid to prevent evaporation and durability without having refill water. High performance & power equal to HITACHI’s high class batteries by using same technology from Japan factory. Expanded grids both Positive & negative are expanded grid for long lasting usage life. Our technology enabled us to manufacture fine particles grids that reduces corrosion of acid with calcium plates, battery reduces water evaporation. Show Less