Precision Radio Controlled Analogue Table Crescendo Alarm Clock White PREC0050. R/C White Alarm Clock Radio Controlled Dial Light Snooze Function 1x AA battery required (not included) 1 Year Manufactures Guarantee. Product Dimensions:- 11.6 x 10.2 x 5.6 cm Item Weight 200 Box Contains 1 × Precision PREC0050 White Radio Controlled Alarm Clock. Precision radio controlled alarm clocks offer the latest in radio controlled time keeping technology in analogue, LCD & LED formats. Precision products are accurate to 1 second in 10 million years, have automatic set up for time and calendar (where applicable), automatic time change for Spring & Autumn and automatic time checks. Precision use The National Physical Laboratory (NPL) which is the UK's home of measurement and the nation's timekeeping. NPL is responsible for operating the national time system and making accurate time available acros the UK. These timepieces keep accurate time by picking up the NPL's radio signal, called MSF, which is transmitted on 60KHz from Cumbria. This transmission carries a date and time code that the radio controlled products use to set themselves to the correct time. The signal is controlled by atomic clocks at the radio station and are adjusted to keep in step with the national time maintained at NPL's laboratory in London.