The Intelli Mixer works so well, I bought two. It offers a large number of mixing patterns / programs, but it does have some limitations. When stacked with larger 50 mL vials, the mass of the rack is too great for the stepping motor to keep up on some of the more aggressive (higher speed) settings. This causes the motor to "stutter" or skip. So if you plan to use this with 50 mL vials, you will need to keep the RPMs down to around 20.That said, the unit has so far performed flawlessly. It does heat up considerably, however, so I recommend allowing it access to generous ventilation.I have used this unit quite successfully for gently mixing thousands of food samples for ICP-MS testing in the Natural News Forensic Food Lab.works great