Multiple eartips are supplied with the H9 Mini headset.  The eartip is fitted onto the end of your headset's earpiece speaker, and placed into your ear when using your headset.

Your headset's performance is greatly dependent upon achieving a good seal in your ear.  There, it is recommended to try all of the supplied eartips with your headset.
To verify you are using the proper eartip, you can leave yourself a voicemail and check for optimal ear seal to ensure a good performance.

Installing the eartips:

When installing an eartip, carefully place it onto the tip of the earpiece speaker