This article is from the Piercing FAQ, by Anne Greenblatt with numerous contributions by others.
The following designs are intended to maintain the enlarged size of
the piercing without the weight of a ring. While these designs are
most frequently worn in ear and septum piercings, some are appropriate
for other enlarged piercings such as nipple, labia, and labret
piercings. Most of the designs are available as small as 10ga and as
large as 3" and in a variety of lengths.
Eyelet / Earlet / Flesh Tunnel / Grommet: A short, hollow tube with
flared ends. The flared ends necessitate that the piercing be
stretched a gauge larger than the gauge of the eyelet for
insertion. Eyelets with one flared end and one straight end, held in
place by a rubber o-ring, are easier to insert. A ring may be worn
through the eyelet to prevent losing the eyelet if it becomes
dislodged. Because the ring must have a diameter wider than the
length of the eyelet, eyelets smaller than 6ga can be difficult to
fit with a ring. Eyelets may be made of metal or glass or wood.
Plug: A short, solid, cylindrical piece of metal, lucite, acrylic,
glass, or wood held in place by rubber o-rings at each end. The ends
of the plug may be grooved to secure the o-rings. The grooves may
get caught on the piercing when inserted.
Threaded Plug / Flatback Plug: Two-piece design made of metal or
acrylic
and internally threaded at one end, similar to a labret stud disc.
 
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