1. Full duplicate communication, call like a phone call 2. Automatic response. The receiver does not need any operation, direct communication 3. One click to speak, after pressing the dialog key, speak directly, the other person can hear 4. Two-way ringtone call, ringtone. 5. Call empty distance test 500 meters (theoretical). Floors 1 to 8. Thin appearance Thickness is only 18mm, the thickness of similar products on the market is more than 22mm, holding a hand feeling. Battery polymer lithium battery, working 5 times a day according to normal, at a time, working for about 30 days, Button adopts plastic + silicone structure, high light UV process, super handy. In contrast to peers, the use is all rubber buttons, no grade and feel. Intelligent and humane design, with intercom lamps and power lamp display, customers at a glance. Normally put on the charging seat when on standby, intelligent charging, never power off. Please note: There may be slight color difference or difference in the actual product, which does not affect the use, please don't mind, thank you! Color: Black Material: plastic Package Contents: 1 * Intercom Doorbell Set Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.