Made of polystyrene Calibrated in 1mL increments from 0.25 to 12mL Tube lip has an extra flare at the top to permit the use of a midget urinometer K-Resin™ urine tubes stand up to the rigors of centrifugation better than standard tubes and are nearly crush-proof, minimizing the chance of costly cleanups from fractured tubes Order Info Caps are available separately