Description :  KERUI C166 Wireless Alarm Watch Pager Waiter Wrist Calling Call Service Wifi Remote Operation for Restaurant   Features :  Lattice screen display、 Chinese & English double language optional、 humanized menu for handling、 easy to learn and use. With a perpetual calendar、 never lose the date and time when power off. Compatible with 999 wireless transmitters、 name of transmitter can be edited. Fit with other type of transmitters、 function of the buttons can be freely defined.  Recently 99 sets of calling information can be surveyed. 10 sets of clock alarm supported、 still alarming when power off. Timing into the power saving mode & power on\/off. Gathering modes like Restaurant、 Hospital、 Bank、 Factory and etc.  Prompt setting with “ Light、 Vibrate、 Beeps” can be optional. Strong power saving technique. Built-in high capacity rechargeable lithium battery. Compatible with coding 1527 ( Resistance 150K-470K) and 2262 (resistance 1.5M-4.7M) the whole series of signal transmitter.         Specification :  Working Voltage: Built-in 3.7V rechargeable lithium battery、 USB-5V to charge Working Current: <3mA Standby Current: <20uA Receiving Frequency: 433MHz Receiving Distance: 60-100 meter (for open area) Working Temperature: -20\u2103 to 55\u2103 External Size: 50 x 45 x 15mm (Not include the watchband)   Package includeds :  1 x KERUI C166 Watch Pager 1 x USB Charger (US \/ AU \/ EU \/ UK plug for Optional~)  1 x User Manual   Details pictures :