Tubes are made in one piece to ensure uniformity and dimensional accuracy from tube to tube. Art. No. 027-300800 is graduated at 1, 2,5 and 4,0ml; Art. No. 027-300400 is graduated at 1, 2,5 and 5,0ml. Centrifugation resistance: recommended between 4,000xg and 7,000xg. All tubes are suitable for laboratory use. Excepting Art. No. 027-300100, which does not withstand centrifugation.