Keepons are sold in pairs. Two identical pieces, one for each of your identical temples. When you examine an actual piece of Keepons, you'll notice that it's essentially a hole with a fin on the side. And because Keepons are made of silicone, the hole is stretchy. We call this stretchy hole the Threading Hole.
Different Keepons have different threading hole diameters. How small or big the hole when unstretched we call the Unstretched Threading Hole Diameter.
Different Keepons have different hole diameters as well as different stretch properties. As a result, different Keepons have threading holes which can fully-stretch to different maximum diameters.
Two identical parts of your eyeglasses which are hinged to your eyeglass lenses at the front of your glasses. Also called the Arms or Stems.
The ends of your eyeglass temples.
The part of your eyeglass temple which curves and rests on your ears.
How wide or narrow your temple tips are, useful in determining which style of Keepons can stretch over and past your temple tips.
How wide or narrow your temple bends are, useful in determining which style of Keepons can sit tightly at your temple bends in order to hook over your ears and anchor your glasses to your ears.