The GVM-FS has a fixed speed of 2500rpm. The small 4mm orbit of the GVM-FS creates a 'vibratory' motion that quickly ensures homogeneity of your samples. With a slight press on the top cup, you can quickly and efficiently vortex virtually any tube. For mixing a larger number of tubes, you can choose constant run and select from a number of compatible accessories preferred for your specific tube format or method. The GVM-FS has a small footprint yet is extremely stable due to its cast aluminum base and available suction cup feet.