/lib/udev/rules.d/85-hdparm.rules is in hdparm 9.54+ds-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1
ACTION=="add", SUBSYSTEM=="block", KERNEL=="[sh]d[a-z]", RUN+="/lib/udev/hdparm"