The true tint.
Sunglasses do two separate jobs, and most of the time only one of them is talked about. A tint dims the light. A polarising filter removes glare, which is a different thing. Tinvero sells one polarised rectangular frame in five tints, because once the filter is doing the second job, the tint is the only decision left, and it is a decision about the light you will be standing in.
Why polarised
Light that bounces off a flat surface, water, a road, a car bonnet, comes away vibrating mostly in one plane. That is glare: a bright veil that carries no information about what is underneath it. A polarising film absorbs that one orientation and passes the rest, so the veil goes and the scene stays. It is why polarised lenses make water look like it has a bottom and a wet road look like a road. A dark tint on its own cannot do this; it dims the glare and the scene together.
Why five tints and not one
Because light is not one thing. Flat bright sun wants a neutral grey that changes colours least. Broken light under trees or on a trail wants a brown that cuts blue haze and lifts contrast. Open water and snow throw light back upward, which is what mirror coatings were made for. Each of the five pairs here is the same frame and the same filter with a different tint in front of it, and each page says plainly which light that tint is for. If you only buy one, buy the grey.
What we know, and what we do not
Every measurement on this site is the frame maker's published figure, and every page that prints one says so. Where a figure is not published — a transmission percentage, a lens category, an exact UV cut-off in nanometres — this site leaves it out rather than filling the row with a number that looks right, which is the more common habit. The UV line says a protective coating is fitted and that no cut-off is stated, because that is exactly what the maker says. There are no star ratings because this shop has no reviews of its own yet. When it does, they will be real ones.
About the imagery
The plain product photographs are supplied with the frames, not taken here. The pictures of people wearing them are renders, not photographs, and every one is captioned as such: the frame in each is the real one, the people, the places and the light are generated. Each render was checked before it went up for the two things generated imagery gets wrong with eyewear, a frame that drifts toward some other design and invented lettering on the temple, and anything showing either was thrown away and made again.
The diagrams are ours, drawn from the published numbers, so the 60mm lens on screen really is wider than the 15mm bridge beside it. When there are photographs of the actual pairs on actual people, taken here, they replace the renders.