Maintenance-free auto batteries are designde to reduce water loss for longer service life.Electrical&Vision Systems are truly maintenance free in that both the positive and negative plates/grids are made of calcium lead-alloys.This calcium/calcium construction reduces gassing and water loss,and,provides superior cranking performance.Other advantages of calcium/calcium construction include prolonged shelf life,greater overcharge resistance and reduced terminal corrosion and the elimination of overfilling or adding harmful impurities.Most Original Equipment batteries for cars and light trucks today,utilize calcium/calcium construction.