What's considered a HR view?

Hello, new to the forums and I can't really find anything that has to do with HR views.
So, I would like to know what is the minimum watch time for a view to be considered HR?

3-4min

Here's what I know:

HR views are views that are played more than 90% - 100% of the length. These are helpful for ranking your video but if YT finds out you're using a service for this, Youtube will flag it as spam. You need to find some quality, highly-authoritative SMM service for these.