the Insta-Set feature of these clock be a little misleading . they be not atomic clock . they do not recieve a external signal to set the clock automatically like a atomic clock . like any other digital clock these clock gain or lose a few seconds a year . they have to be set occasionally . Google `` reset equity insta-set clock '' for instruction . basically , you hold down the DST or Alarm Set button for five seconds . you can then set the hour , minute , month , day ... like other digital clock . the documentation never say specifically what Insta-Set mean . apparently be just mean the clock do not have to be reset after a power outage . it have a internal battery that hold the time until the main power come back on . other than this misleading name for the insta-set feature the clock I have work well . it be worth what it cost .