1、ULTRA LONG WORKING DISTANCE: The wireless doorbell has long distance transmission and high strength signal and sensitivity, and the maximum opening distance can reach 100m. Make sure you hear and answer the doorbell on time, you'll always be easily notified when someone calls from outside and never have to worry about missing a visitor 2、EASY INSTALLATION AND EXPANSION: Use the included screws to attach this outdoor doorbell to your door or wall for security. Wireless intercom doorbells are scalable, so you can scale almost any indoor or outdoor system, even up to a set of 2 transmitters and receivers 3、EASY TO INSTALL AND PAIR: Just tape the wireless doorbell directly to the wall. By learning the code, 1 outdoor bell can be paired with multiple indoor bells without interfering with other devices in your home or neighborhood 4、LOW POWER CONSUMPTION AND SAFE USE: Two way intercom doorbell with up to six months of outdoor bell standby time 5、WIDELY USED AND ADJUSTABLE: Wireless doorbell kit is suitable for homes, apartments, schools, villas, offices, warehouses, hotels, factories, hospitals, etc. Adjustable speakers provide clear and loud sound and can be used as mobile walkie talkies Item Type: 2 Way Voice Intercom Doorbell Operating Temperature: -20℃~55℃ Transmission Distance: Approx. 100m / 328.1ft open; Partition wall approx. 5 ~ 20meter / 16.4 ~ 65.6ft Operating Frequency: 433MHz 2 x Doorbell Internal Machine 1 x Screwdriver 1 x User Manual