1.[ No Free Acid ] All of the electrolytes are absorbed into the positive plates, negative plates, and the micro porous glass fiber mat. There is no free acid inside the battery, therefore the VRLA battery can be mounted in any location. 2.[ Safe and Sealed ] The unique construction and sealing technology ensure that no electrolyte leakage can occur from the terminals or cases of any VRLA batteries. 3.[ Maintenance-Free Operation ] During the expected service life, there is no need to check the specific gravity of electrolyte or to add water.