How to run systemd timer every two hours

The syntax to run a systemd timer every two hours is:

OnCalendar=*-*-* 00,02,04,06,08,10,12,14,16,18,20,22:00:00

i.e. run it on the first minute and first second (00:00) of every second hour (00,02,04,06,08,10,12,14,16,18,20,22).