Etymotic ER•4® microPro® Earphones - Manual (Page 5)

4
ABOUT ET YMOTIC RESEARCH SELECTING AN EARTIP
The eartips that are most comfortable are the best choice, but they
should seal well in the ears for best noise isolation and sound quality.
When changing eartips
make sure the eartip fits
securely on the stem of
the earphone.
correct
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Foam Glider 3-flange
incorrect