These premium quality general purpose centrifuge tubes are available with molded-in graduations, or for exceptional reading ease, printed graduations. Large writing area on printed tubes makes identification simple. Molded in seal-ring ensures a leakproof seal without the contamination problems associated with cap liners. 15 mL tubes are available in polystyrene or polypropylene. Polystyrene offers glass-like clarity and can withstand 1800 RCF. Polypropylene has excellent chemical resistance and can withstand 6400 RCF.