The Pyrex 5640 25ml Class A Volumetric Flask is a high-quality lab flask made of borosilicate glass, known for its durability and resistance to thermal shock. This flask is designed for precise measurements and is suitable for use in various disciplines such as physical, dental, medical, microbiological, and biological laboratories. Without a stopper included, this flask is ideal for accurately measuring and storing liquids in a laboratory setting, making it a reliable tool for scientific research and analysis.