KERUI Wireless Paging Calling Service System for Bank,Restaurant,Hospital,Factory,Hospital,School,Construction Site,Hotel Guest Room,Office needs of waiter,Pack of 24 Buttons and 4 pcs Watches Compatible with 999 wireless transmitters, name of transmitter can be edited,in our shop,there are some buttons you can choose,also we can customize the product for you as your needs. Easily Installed-can be installed on each table,when the guest needs any service, he or she just press the button on the table, his or her table number will show on the watch and there are three reminder ways for you choose:lights,beep,vibration),then the waiters will go and offer best service in time. Highly anti-interference and stable performance,the watch pager adopt a high-speed CPU processing & high sensitive wireless receive technology. Receiver watch Working Voltage:Built-in DC 3.7V rechargeable battery,USB-5V to charge;transmitter button working voltage:Two CR2016 3V lithium batteries.Battery life:at least 48h on standby & 24h in using.Transmission distance: 100m(328 ft) in the open air,but if there are some barriers,the distance will reduce a half,while the distance is too long and signal not so stable,may be you can add a signal repeater,this ASIN(B00V7WP1BI)FYI. Wireless Paging System-It is widely used for restaurants, bars, Internet cafes, tea house, cafe,hospitals, clinics, nursing homes, nursing homes, Banks, schools, factories, construction sites, hotels, hotel rooms, enterprises and institutions and residential buildings and other places of call services