Units provide gentle overhead movement for wastewater and sludge analysis. They are designed for the easy and fast attachment of bottles and vessels. One-dimensional swirling action is continuously adjustable from 1–16rpm. Units have analog dial control of rpm adjustment. The maintenance-free, balanced, sealed drive system is isolated from spills, which makes these shakers ideal for use in cold rooms. Units are designed for continuous use and will self-reset to protect against overheating.