Wireless Doorbell Button with 3.7V rechargeableLithium battery

Wireless Doorbell Button with 3.7V rechargeableLithium battery Model:CX-82 Wireless Doorbell Button Features : Nice outlooks design, Micro power special CPU; 3.7V rechargeableLithium battery, low battery, low power LED indication; CX-89:Send signal to alarm host for emergency alarm. CX-82:Send signal to alarm host to make door chime. Wireless Doorbell Button Specifications Emitting Distance: ≥150M(in open area) 433/868 MHZ optional