The STM-100 mixer ensures a smooth rocking action for consistently uniform specimen suspension. The reversible pad provides one side for capped tubes 100mm long (lip on end of pad prevents tube from sliding) and other side for longer tubes. A white silicon rubber, friction grip pad creates contrast between specimens and labels for easy viewing. Capacity: 16 tubes; Mixing Surface (WxL): 4.5? x 12.0?; Overall dimensions(WxHxD): 15.0? x 4.25? x 5.5″; Weight: 5.75 lbs.