The La Crosse Technology 21" Atomic Indoor/Outdoor Wall Clock combines precision timekeeping with environmental monitoring in a large-format design suitable for both indoor and outdoor use. At 21 inches in diameter, the clock is easy to read from across a room, patio, or garage, making it ideal for kitchens, covered porches, workshops, and large living spaces.

This clock uses atomic timekeeping technology, automatically syncing to the WWVB radio signal broadcast by the National Institute of Standards and Technology (NIST) for accuracy to the second. It automatically adjusts for daylight saving time and supports multiple U.S. time zone settings, eliminating the need for manual time adjustments. A manual setting option is also available for areas where the signal may be weak.

In addition to the time display, the clock features an analog thermometer and hygrometer, displaying both indoor and outdoor temperature (in °F and °C) and relative humidity. The lighted display ensures visibility in low-light conditions. The clock operates on a single AA alkaline battery (not included).