Light because it is small

Every eyewear brand with a lightness claim makes a material claim. Titanium, beta-titanium, magnesium alloy, some carbon composite with a number after it. The implication is that weight lives in the substance.

Mostly it does not. Weight lives in area, and area is a shape decision made long before anybody picks a metal.

What we did not build

The obvious frame for a product used outdoors is a sports wrap. Thick rim, wide front, big curved lens, the whole vocabulary of performance eyewear. It is also heavy, and the heaviness compounds: a wide frame forces a wide lens, and lens area is where mass accumulates faster than anywhere else in a pair of glasses.

We used the proportions of an ordinary indoor frame instead. Smaller rim, smaller lens, and the weight saved at the source rather than clawed back by an exotic material afterwards.

The cheapest gram to remove is the one you never designed in.

There is a second benefit, and it is the reason the shape survived every review. An indoor frame does not look like equipment. Sports eyewear announces that you are doing something athletic, which is a bad thing for a product you are supposed to keep on when you walk into a café.

Why not titanium

Because of what is inside the frame. There is a microphone moulded into the front, with its port, its acoustic cavity, and a wiring channel that runs through the nose bridge and across a hinge. Both temples are full of electronics — battery, board, button, charging contacts.

Threading all of that through a metal frame is a harder problem, and we could not find the gain that would justify taking it on. Metal also conducts heat, transmits handling noise into the microphone, and is significantly less forgiving when somebody sits on it.

What TR90 actually is

The word "nylon" suggests something cheap. TR90 is the material high-end American outdoor eyewear is built from: very light, very high in resilience, and it flexes back to shape instead of taking a set. Drop it and it survives in a way acetate does not.

It is also demanding to mould, which is why the front frame and the temples each get their own steel tool rather than aluminium. TR90 flows poorly and needs careful venting, and aluminium tools blur exactly the details — the port, the cavity, the hinge interface — that we are spending the money to get right.

Where this lands

In the same class as the titanium frames marketed as the lightest available. Not because TR90 beats titanium on density, but because a smaller lens in a smaller rim gives back more than the material difference takes away.

And past that point the comparison stops being interesting. Once a pair of glasses is already light, five grams is not what decides whether somebody can wear it for four hours. Fit decides that. So does how the mass is distributed — ours sits in the temples, spread across both sides, which reads on a face very differently from the same mass sitting on the bridge of a nose.

Some people find any glasses uncomfortable and some people forget they are wearing them, and no specification sheet has ever predicted which one you are. What a specification sheet can do is stop the product from being the reason.