Safer and more accurate than conventional filling. Install in minutes without tools. Just replace the battery caps with the valve manifolds connected with flexible tubing. Automatically sends water only to low cells. Automatic shut-off at each cell prevents over-fill. Provides electrolyte level accuracy to 1/8". Makes maintaining proper electrolyte levels in hard-to-reach batteries easy, improving battery life and performance and preventing dangerous acid bubble-out during charging. Flame arrestors prevent external spark or flame from igniting flammable cell gasses. Pumps work with any distilled water container. Reusable systems can be installed on new batteries when old batteries are replaced. USA.