30 pcs bell 1 display service waiter call transmitter and receiver

Brand Name: Singcall
Frequency: 433Mhz
Working voltage: 9V
Capacity: 500
Distance : 500m
Receiver weight: 0.9KG
Working current: <1A
Receiver size : 23*16*4cm
Button size: 60*60*20mm
Button material: ABS+silicon
Button weight: 40g(including battery)