Tempered glass against the heat
Duralex makes its glasses from tempered glass: by cooling the surface quickly, the outer layer is put under compression, so the glass takes far more knocks than ordinary pressed glass. If it does break, it falls apart into blunt granules rather than shards, and that is exactly why these glasses are found in school canteens and hospitals. Thick-walled pressed glass from La Rochère is not tempered but it is heavy, and mass alone is enough.
Everything on this page is dishwasher safe. Put stackable glasses in the rack separately, not nested, because water otherwise stays trapped between them. Over time tea leaves a brown deposit on the bottom. You remove it with soda in hot water and a brush, not with scouring powder, because that leaves the glass dull.