Pack of 10 stoppers made of neoprene rubber. Each stopper has a single hole measuring 5mm in diameter. Blue color. Each stopper measures 40mm in length, has a base diameter measuring 40mm, and a top diameter measuring 49mm. The neoprene rubber construction is suitable for use with petroleum products, minerals, oils and fats, as well as most inorganic acids and bases. Resistant to temperatures ranging from -40 to 130°C.