Viking’s CL Series wireless clocks include automatic calibration, as well as clock-based diagnostics that allow the user to view the signal strength, how long since the clock received a signal, mechanical / display issues, and remaining battery life for Analog clocks. The 12 and 16" wireless Analog clocks receive and retransmit an RF syncronization signal every 2 hours (standard mode) or 4 hours (economy mode) allowing for a battery life of 5 years or 8 years respectively. The 2.5 and 4" digital clocks are powered by an included power adapter and receive and retransmit an RF clock sync signal every minute. Viking also offers a complete line of accessories for the Analog or Digital clocks such as-double mount housings, wire guards and surface mount housings (for digital clocks only).