It is becoming increasingly difficult to distinguish between the laboratory rocker and orbital shaker.
Both are used for mixing and preparing samples, but the essential differences have been blurred so that speed is usually the defining factor (need an orbital shaker? Look here)
Laboratory rockers tend to operate at lower speeds since they are better suited for washes and staining and not vigorous shaking.
Rockers offer two options which depend on preference and sometimes space considerations, rather than an actual distinction in performance.
This category has been broadened to include a number of tube roller and rotator options as well.