Ring video doorbell ( 2 GEN )

Good evening I have been given a ring video doorbell (2nd gen) this is the doorbell that has to be removed for charging, the bell it's self is working ok but i have to remove it quite often to change the battery, ( 5 / 6 days ) I am looking for advice To hardwire my doorbell, i would like to know which is the best transformer for the job and the basic wiring instructions thank you very much for any help you can give me.