Eisco Watch Glasses - Eisco CH0554D, These 90mm diameter watch glasses are highly functional items of glassware that have a variety of uses in the classroom or laboratory. They are essentially very shallow glass saucers and work well as lids for flasks and beakers, or for holding small samples for observation under a low-power microscope. They are also ideal for evaporating liquids from samples, such as when growing seed crystals, and can be used for making lenses from ice or other liquids.Eisco watch glasses are manufactured with sturdiness in mind. Their 2mm thick construction resists shattering and as they have ground edges, as well as a polished surface, so you can be sure that they are a safe product to handle in the classroom or the laboratory. Eisco Watch Glasses 90mm Pack of 10