Item Type: 2WayVoiceIntercom Material: ABS Model: H8 Battery: Rechargeable Lithium Battery 3.7V 2000mAh (Built in) Use: Widely used in household, office, laboratory environment, medical treatment, etc. Basic Parameter: Working Temperature: -20℃ to 55℃ Transmission Distance: 1000m in open area, 20 to 50m through wall Operating Frequency: 410M to 490M DOORBELL UNIT: The pack contains 2 pcs doorbell system units, which can switch between ringtone call and intercom mode. INTERCOMUNICADOR FUNCTION: the two units can be used as intercomunicador for two way talk without shouting at home. LONG RANGE: The transmission distance of the voice intercom device can achieve 1000m in open area and 20 to 50m through wall, highly practical. INDICATOR LIGHT: The voice intercom units are humanized designed with intercom light and power light, users can see clearly at a glance. LONG BATTERY LIFE: The 2 way voice intercom has built in large capacity battery, adopts intelligent power saving chip, with long battery life.