Reagent bottles, also known as media bottles or graduated bottles, are containers made of glass, plastic, borosilicate or related substances, and topped by special caps or stoppers and are intended to contain chemicals in liquid or powder form for laboratories and stored in cabinets or on shelves. Some reagent bottles are tinted amber (actinic), brown or red to protect light-sensitive chemical compounds from visible light, ultraviolet and infrared radiation which may alter them. The bottles are called "graduated" when they have marks on the sides indicating the approximate (rarely exact) amount of liquid at a given level within the container. A reagent bottle is a type of laboratory glassware. The term "reagent" refers to a substance that is part of a chemical reaction (or an ingredient of