Feature:1. 20Pcs Call Buttons: This wireless calling system set provides 20pcs waterproof call buttons, 1 PC display receiver, 20pcs x sticker, and 1 adapter.2. Wireless Technology: This patient pager system adopts radio frequency wireless technology which ensures stable performance and long distance.3. Powerful Receiver: This patient pager system provides 1 PC display receiver which supports 400 call buttons.4. Adjustable Volume: The volume of this customers pager system is adjustable in 30 levels, meeting different needs.5. Wide Application: This wireless calling system is perfect for restaurant, nursing home, cafe, supermarket, hotel, hospital ward, emergency center, bank, school, factory, construction site.Specification:Item Type: Patient Pager SystemMaterial: ABSDisplay Receiver Parameters:Operating Frequency: 433.92MHzOperating Current: <130mAStandby Current; <550mAModulation Mode: ASKReceiving Sensitivity: Better Than -105dBDecode: Study CodeWaterproof Grade: IPX4Operating Temperature: Minus 20 to 60Button Transmitter Parameters:Operating Frequency: 433.92MHzAlkaline Battery Model: 12V23A (Included)Battery Capacity: 30mAhTransmitting Current: 10mA3mAStandby Current: <1uAOpen Space Distance: >200 Meters / 218.7ydKeys: A Million TimesWaterproof Grade: IPX7Operating Temperature: Minus 20 to 55Single Button: Call.Package List:1 x Receiver20 x Call Buttons20 x Sticker1 x User Manual1 x Adapter