Brand New 16.5V 40VA Burglar Alarm Systems & Doorbell Transformer ELIMINATATE DOORBELL UNDER POWER HASSEL:16.5V 40VA plug in transformer, replaces and upgrades underpowered transformer with this 16.5V AC transformer, offering plenty of power for your doorbells ➡Compatible With: This transformer compatible for Honeywell Ademco, DSC, ETC Burglar Alarm Systems; Also compatible with Video Doorbell, Video Doorbell 2, Video Doorbell Pro, Nest Skybell Doorbell, Note: The brand above is only for demonstrating compatibility Easy to install: Output with screw terminals, simple wiring。The load voltage (when the doorbell is running) is 16.5V & the output of no-load voltage by a multimeter to test is about 18.5-19.5V, normal function & won’t affect use. When testing use an AC voltmeter or multimeter to test the output & a voltage tester to measure the accurate voltage output.