Valcom 16inch, 24VDC Round Wired Analog Clock Microprocessor based movement - 2 or 3 wire correction - Automatic communications protocol identification for: Valcom 2 wire digital protocol; synch-wire 59th minute correction; synch-wire 58th minute correction; synch-wire national time and rauland - Diagnostic leds for ease of maintenance - Fully automatic plug and play--no settings required - Built-in self-test function - Automatic polarity detection - Quick correction - Energy efficient - UTP connectivity - Plug in molex connectors - Low profile - Metal case with polycarbonate crystal - Made in USA - UL, CUL, and FCC approved