1、The frequency of use of this product is in accordance with national regulations and will not cause harmful electromagnetic interference, which is universal worldwide. 2、Outdoor‑bell is power supplied by 4pcs AAA battery (not included), easy to replace the battery. Indoor‑bell is used with an external USB data cable. 3、Low power consumption, long standby time for outdoor‑bell up to 4 months. 4、Big and adjustable speaker, clear voice, can be used as mobile interphone. 5、Long working distance, the maximum open distance can reach 200m / 656.2ft. 6、Easy installation, stick directly to the wall with adhesive tape. 7、Outdoor‑bell pair with indoor‑bell by learning its code, 1 outdoor‑bell can paired with 2 indoor‑bells and no interference each other. 8、Made of ABS plastic, exquisite and small, beautiful and high grade. Condition: Item Type: Door Bell Material: ABS Plastic Color: As Pictures Shown Outdoor-Bell: Voltage Range: 4 x AAA batteries (not included) Working Temperature: -20-55℃ Transmission Distance: Approx. 200m / 656.2ft in the open, 5 - 50m / 16.4 - 164ft in obstacles Working Frequency: 467.6375MHZ Working Time: 4 Months Waterproof Level: No Waterproof Function Indoor-Bell: Voltage Range: 5V 1A Working Temperature: -20-55℃ Transmission Distance: Approx. 200m / 656.2ft in the open, 5 - 50m / 16.4 - 164ft in obstacles Working Frequency: 467.6375MHZ Waterproof Level: No Waterproof Function 1 x Outside Doorbell 1 x Inner Doorbell 1 x Screwdriver 1 x Manual 2 x Sticker Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.