They close the gap at the temple, nothing more
A pair of glasses stops what comes straight at you. The opening between the lens and your cheekbone is where a chip of wood, a splash of solvent or a flake of grinding dust arrives from, and that opening is what a side shield covers.
They are a sensible addition for woodwork, light lab work, workshop cleaning and garden strimming. They are not a substitute for sealed goggles where the hazard is a liquid under pressure or a high-velocity particle.
How the clip fits almost any frame
The clip is a soft TPU channel that grips the arm rather than the lens. It flexes around a thin wire temple and opens far enough for a thick acetate one, which is where the 98 percent of eyeglass frames figure comes from.
Fit them with the glasses off, slide the shield back until it meets the hinge, and then put the glasses on. If the shield touches your eyebrow, it is too far forward by about a centimetre.
Clear, or coloured on purpose
Clear shields disappear in use and are the default. The tinted versions — blue, green, brown, pink — exist because in a shared workshop or a teaching lab, colour is how you tell whose glasses are whose at the end of a session.
Whichever you pick, the material is the same and so is the coverage. Colour here is an identification feature, not an optical one.
Keeping them usable
Wash them in warm soapy water and let them air dry; solvent will haze the surface and a paper towel will scratch it. If a shield goes cloudy, replace it rather than polishing it, which is why we sell them in packs of three and six.
Store them clipped onto the glasses case rather than loose in a drawer. They are small, light and extremely good at disappearing.