Feature:1. 3 Levels Of Volume Adjustable: The elderly can also hear, the highest volume is not less than 112 decibels, whether in the bedroom or in the kitchen can be heard, builtin 30 ringtones, a variety of tunes to choose from2. 2000M DISTANCE: Using professional chip, the theoretical call distance can achieve 2000M in flat and open areas, making your contact more convenient.3. WIDE SIGNAL COVERAGE: Adopting 462MHz radio frequency, the signal coverage is wider and wall crossing is simpler.4. LONG ENDURANCE: Both the indoor and outdoor units are equipped with 1800mAh rechargeable lithium batteries, ensuring long lasting battery life.5. ANTI INTERFERENCE: With 16 separate channel options, this wireless doorbell can easily avoid interference in wireless frequency bands.Specification:Item Type: Wireless Voice DoorbellMaterial: ABSPower: 0.5WChannel: 1-16Number of Connections: Up to 16 sets without serial numbers, unlimited connections under the same channel numberBattery: 2 x 1800mAh rechargeable lithium battery, 1 battery per host (shipped with built in battery).Package List:1 x Indoor Unit1 x Charging Base1 x Outdoor Unit1 x Outdoor Unit Bracket1 x USB Cable1 x Double Sided Adhesive1 x Doorbell Sticker5 x Screw3 x Anchor