These Polystyrene (clear plastic) Centrifuge tubes have exceptional reading ease of the printed graduations, and the large writing area on the tubes makes identification simple. Polystyrene offers glass-like clarity and can withstand 1500 RCF.  Molded in seal-ring ensures a leak proof seal without the contamination problems associated with cap liners. Includes screw cap. Measures 119mm (L) x 22mm (D) with the cap intact. The diameter measurement is taken at the widest part of the cap.