PYREX 50 mL Round Bottom Centrifuge Tube with Standard Taper Pennyhead Stopper Case of 12 $471.13 Quantity discounts available QuantityPrice SKU: COR-8424-50 Quantity -+ Add to Cart Details These 50 mL PYREX round bottom, nongraduated centrifuge tubes have a No. 13 Standard Taper solid glass pennyhead stopper. Rockefeller Institute of Med... Details Back DetailsThese 50 mL PYREX round bottom, nongraduated centrifuge tubes have a No. 13 Standard Taper solid glass pennyhead stopper. Rockefeller Institute of Medical Research type.