The LM500 maintains oil level on any size engine. As crankcase oil level drops, the LM500 float also drops and opens the Thumb-Valve. This allows oil to flow from the supply tank, through the LM500, and into the crankcase. When proper level is achieved in the crankcase, the LM500 float rises, causing the Thumb-Valve to close off further oil flow. The simple and unique Thumb-Valve is non-clogging and provides a positive, leak-free seal. It also supports installations that require a 3-wire, snap-action switch. The LM500 series maintains the crankcase oil level of an engine, pump or compressor. Adjusted to the correct running-oil-level, it will replenish oil as it is used. The low-level switch will alarm and/or shutdown the equipment if supply oil is lost and the equipment continues to use oil. The LM500 is made of die cast aluminum and features a clear "frog eye" high impact lens which allows the operator to view the oil level and condition without shutting down the equipment.