> in my hand

That's the important part you're missing.

Having it always looking in the direction your head is facing is an advantage of the head mounted form factor even if it doesn't depend on the eyepiece display.

Not needing a hand to look at the output is an advantage of the eyepiece.

So, yeah, the glasses do make a difference over a smartphone in this use case.

A specially made hand held device could do it too, but it would still be a problem because you're using hands.

Could put it on your wrist, like QBs have. A fragile device on your head, over your eyes, still doesn't seem like the best solution.

Most safety equipment is designed for glasses and also works with google glass. Further, you want nothing strapped to you when dealing with heavy machinery not even a watch which means you would need to keep it in a pocket and use your hands to manipulate it.

PS: Even rings have cost many people their fingers.

> manufacturing industry

> in my hand

Gloves, dirty and thick.

TEMBA, HIS ARMS WIDE