The speaker volume is adjustable: the meter's speaker is loud and adjustable with clear sound. It can be easily mounted on the wall with adhesive tape, ideal for transmission distances up to 200 meters without interference. Perfect combination: the indoor intercom is perfectly combined with the outdoor intercom, allowing you to speak to visitors outside your door. The doorbell sound effect is greatly enhanced, allowing you to identify visitors outside the door by the sound. 3W power: The meter intercom The dual-way system is designed with electro-acoustic circuit devices, improved sound quality, and a high output power of 3W for the main and sub units, providing clear, bright sound and high voice resolution. Fully automatic call control: The two-way window intercom system employs fully automatic call control, utilizing duplex voice intercom conversation technology, automatic voice signal recognition and processing; the call process requires no operation.