. Bell button with LED light signal (can be used for Comfort and Premium set). Installation type of bell button: surface mounting using screw or adhesive strip. Radio range: 100 meters in open space. Bell button: power supply 1 x 3 V battery (CR2032) included. Frequency band: 433.05 - 434.79 MHz. RF power level: 10 mW. Protection class of doorbell button: IP 44. Color: pure white