
United Scientific® Self-Standing Centrifuge Tubes, 50 mL, Sterile by United Scientific are flat-bottom polypropylene tubes with leak-proof blue HDPE screw caps, sold 500 per case. They are gamma radiation sterilized, DNase-, RNase-, pyrogen-, and latex-free, and rated to 9000 RCF. Life science and clinical research labs use them for samples, aliquots, and media that need to stand upright without a rack.