Before Installing I asked do I need a Transformer? He said No!! the door bells only work for two-days, we went through this many times. Until Monday 4/5/21 the guy from Corporate told me the truth and said that they should never have been Installed!! Brinks, needs to either fix it that it works, or come get this equipment and return all monies paid. User's recommendation: Try to make sure that they are giving you something that you pay for, more than two-days.