… optical elements, of any material, unmounted, other than such elements of glass not optically worked. …
Explanatory notes
… optical elements, of any material, unmounted, other than such elements of glass not optically worked. 9001.10 ‑ … of glass is usually performed in two stages, viz., the production of the surfaces to the shape required (i.e., with … of abrasives, rough at first, then gradually finer, the successive operations being roughing, trueing, smoothing and …