I'm sort of ambivalent regarding the grip ring (some people seem to not like it) but I did order some spacer rings which can be used on either the TK12 or TK15 if you replace the grip ring.

Like the TK12, the TK15 comes with both a pocket clip and "cigar grip ring" which allows a better grip when holding the flashlight like cigar or plunger - both the clip and grip ring can be removed.

This grip is working with ring crush tester to test the column compression strength.