Feature: 1. 2 Usage Ways: This wireless intercom system has 2 independent usage ways: press the green button to hear the other, or press and hold the PTT button to speak directly, meeting different usage needs. 2. Transmissing Distance: The transmissing distance is up to 1000 meters in the open area and 20 to 100 meters through the wall, 1‑8 floors, with strong practicality and suitable for most scenarios. 3. Battery Powered: Built in 3.7V polymer lithium battery, 1800mAh large capacity, it can work 5 times a day for 30 seconds each time for about 1 week, placeing on the charging base during standby. 4. Gear Switching: 0 gear indicates shutdown, A gear indicates 462MHz frequency, B gear indicates 434MHz frequency. If there is interference during the call, you can switch A gear or B gear. 5. Button and Volume: The button is made of plastic and silicone materials, with high gloss UV process to ensure a comfortable touch. Supports 3 levels ringtone volume and 3 levels call sound adjustment. Specification: Item Type: Wireless Voice Caller Battery: 1 x Polymer Lithium Battery 3.7V 1800mAh (Built in) Battery Power Supply: DC5V 1A Working Temperature: -20℃ to 55℃ Transmissing Distance: Approx. 1000m / 3280.8ft open space, 20-100m / 65.6-328.1ft through wall, 1-8 floors Working Frequency: 410-490MHz Working Time: About 3 days on a single charging Charging Time: About 5 hours for full charging Music Ringtone: 38 Ringtones Ringtones Volume: 3 levels adjustment (adjust volume key in standby mode) Call Sound: 3 levels adjustment call volume (adjust volume key during call) Product Size: Approx. 116 x 56 x 18mm / 4.6 x 2.2 x 0.7in Charging Base Size: Approx. 70 x 56 x 29mm / 2.8 x 2.2 x 1.1in. Package List: 2 x Internal Units 2 x Bases 2 x Data Cables 1 x User Manual