Ultracentrifuges are laboratory centrifuges with rotors that spin at very high speeds, usually ranging from 60,000 RPM and 200,000 x g to 150,000 RPM and 1,000,000 x g. Ultracentrifuges are segmented into two main classes, preparative and analytical. Preparative ultracentrifuges isolate or pellet biological particles, viruses, organelles, membranes and biomolecules such as DNA, RNA and lipoproteins. Analytical ultracentrifuges use detection systems to monitor spinning samples in real time to determine sedimentation velocity and equilibrium used to determine shape and mass of macromolecules. The below instruments are preparative ultracentrifuges. When purchasing ultracentrifuges be aware of the techniques and applications you’ll perform now and in the future; research available rotors, rotor compatibility and temperature range. Other features to look for include remote monitoring and control, and user password protection.