Like how warm/ hot liquids are which lasts about 1/2 hour. Like being able to see liquids in clear view. Like how light weight the mug is. I do feel that dishwasher may break them down after awhile and make them more susceptible to shattering. If one does break watch out for lots of tiny shards of glass. Wear footwear immediately. They do not get stained from liquids like inside of other mugs do.