Wireless intercom dobell - 1 outdo dobell can be paired with 1 indo dobell, the perfect combination allows you to communicate with visits at your do. Intercom Two-Way - When someone presses the call button on the outdo unit, the indo buzzer will ring immediately to remind you. You can press the answer button to talk to someone outside. Clear voice - Built-in high-sensitivity microphone speaker, the signal 2.4 GHz provides clear fluent sound effect when communicating. Effective transmission distance up to 300 meters Easy to use - Ultra mini size ensures perfect ptability easy installation, small beautiful, easy to install. Suitable f home, facty, hotel, hospital, supermarket office. adventure Product transmission distance: 200 meters in open space; 5-50 meters if there are obstacles. feature 1. The frequency of use of this product complies with national regulations will not produce harmful electromagnetic interference. It can be used universally. This device complies with FCC, CE CCC rules regulations. 2. The outdo unit is easy to install battery-remove, using 4 AA batteries (batteries not included), the indo unit uses a rechargeable lithium battery. The outdo chime is powered by 4 alkaline batteries f easy battery replacement 3. The outdo unit has a long service life, 4 batteries can be used f me than six months. Low power consumption, outdo bell stby time up to six months 4. Speaker sound, adjustable volume, changeable ringtone, clear intercom sound quality, can be used f mobile intercom. The speaker is adjustable, the sound is clear it can be used as a mobile phone walkie-talkie. 5. Long wking distance, the maximum opening distance is 200 meters. Ultra-long wireless distance up to 200M 6. Easy to install, directly stuck to the wall with 3M glue. Easy wall mounting with 3M adhesive tape 7. Through code-to-code learning, one outdo unit suppts N indo units without interfering with each other without changing the code. By learning the code, the outdo chime can be paired at the interi chime. An external ringtone can be paired with N internal ringtones without interfering with each other. 8. Exquisite small, beautiful generous. Size : 1006014.8mm Note: The data is all manual measurement, please allow 1 - 3cm err, due to the difference in light display, there will be some col difference, depending on the physical object received Delivery Quantity: (accding to the main picture)