• Fits glass, plastic, and blood test tubes
• Seals inside test tube or over tube rim

Firm, positive closure is designed for test tubes, blood drawing tubes, and round-bottom centrifuge tubes. Also prevents evaporation. Closure will not crack or pop off. The 12 and 13 mm closure covers either 12 mm or 13 mm tubes, and when reversed, stoppers 10 mm tubes. The 16 mm closure covers 16 mm tubes, and when reversed, will stopper 12 mm and 13 mm tubes.