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 LSASHOP Wireless Intercom Unit For Home Voice Intercom Super Long Range, Black 2 Pack 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 areas and 20 to 50m through walls, highly practical Indicator Light: The voice intercom units are designed with intercom light and power light, allowing users to see clearly at a glance