school electric bell 1 CE certificate 2 voltage can be custom 3 professional in this filed for 17 years

school electric bell1) Alarm of easy combustion causticity air or conductive dust 2) The surrounding temperature does not exceed 40°C3) Bear to press: 1,500V, 50 times/a minute4) Electric resistance: shouldn't be small than 10Ω5) Settle the electric voltage ±10% 6) Switch every 5 minutes7) Work time: not longer than 5 minutes8) Uninstall the bell cover to move absolutely

school electric bell