deb http://deb.debian.org/debian/ buster main contrib non-free
deb http://security.debian.org/ buster/updates main contrib non-free

# buster-updates, previously known as 'volatile'
deb http://deb.debian.org/debian/ buster-updates main contrib non-free

# buster-backports, previously on backports.debian.org
deb http://deb.debian.org/debian/ buster-backports main contrib non-free