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 System Material: ABS Display Receiver Parameters: Operating Frequency: 433.92MHz Operating Current: <130mA Standby Current; <550mA Modulation Mode: ASK Receiving Sensitivity: Better Than -105dB Decode: Study Code Waterproof Grade: IPX4 Operating Temperature: Minus 20℃ to 60℃ Button Transmitter Parameters: Operating Frequency: 433.92MHz Alkaline Battery Model: 12V23A (Included) Battery Capacity: 30mAh Transmitting Current: 10mA±3mA Standby Current: <1uA Open Space Distance: >200 Meters / 218.7yd Keys: A Million Times Waterproof Grade: IPX7 Operating Temperature: Minus 20℃ to 55℃ Single Button: Call. Package List: 1 x Receiver20 x Call Buttons20 x Sticker1 x User Manual1 x Adapter