The Dillon Primer Early Warning System is a sensor to alert the user when the primers run low on their Dillon progressive reloading machine. The sensor sounds an audible low-pitched warning before the primers are actually used up.
The Early Warning System is included with each of the Dillon progressive reloading machines (not applicable to the SL900, nor the BL550).Additional systems are convenient when exchanging priming systems from large to small, or vice versa, especially on the XL650.