The ST-919 set includes a SUITA wireless doorbell and a wireless button. Ideal as a doorbell or internal paging device, useful at home, company or people in need of care, no bell installation required, easy installation, radio transmission (433, 92MHz), operation range*: 80 m in open area, coding: 256 codes ( code set by the factory, the code cannot be changed by the user), bell and button battery-powered, button not adapted to work in changing weather conditions, sound: 15 melodies to choose from (polyphonic ringtones), sound level: 80 dB. *The given operating range applies to open space, i.e. ideal conditions, without obstacles. If there are obstacles between the receiver and the transmitter, it is necessary to anticipate a reduction in the operating range for: wood and plaster by 5 to 20%, brick from 20 to 40%, reinforced concrete from 40 to 80%. With metal obstacles, the use of radio systems is not recommended due to a significant reduction in the operating range. Overhead and underground high-power power lines as well as GSM network transmitters placed in close proximity to the devices also have a negative impact on the operating range.