Our analog wall clock is accurate to 1//10,000 of a second and automatically sets itself. It receives a controlling radio signal directly from N.I.S.T.’s atomic clock in Boulder, Colorado, to adjust clock for daylight saving time and leap seconds. The bright second sweep hand is highly visible. It is supplied with wall mount, screw, and AA battery. A certificate is provided to indicate instrument traceability to standards provided by NIST. Calibrated by an ISO 17025 calibration laboratory accredited by A2LA.