La Crosse Technology Ws-8418Al-It Atomic Digital Wall Clock With Moon Phase, Aluminum Atomic indoor wall clock with moon phase and indoor/outdoor temperatures; time resets according to WWVB radio transmissions Aluminum square frame around large, easy-to-read LCD; alarm clock function with 10-minute snooze Outside TX37U-IT sensor transmits data at 915MHz from up to 330 feet away; manual time-set option Requires separate purchase of 4 AA batteries; low battery indication icons for both clock and sensor Clock measures 10-1/4 inches wide by 1-1/6 inches deep by 9-3/4 inches high; 1-year limited warranty Please refer user manual attached below for instructions and troubleshooting steps.