The PTWS D620 is a “Dual Drive” 6+6 position, tablet dissolution testing instrument for solid dosage forms as described in USP chapter <711/724> and EP section<2.9.3/4> as well as the DAB/BP and Japanese Pharmacopeia section <15>. The instrument features two additional vessels (approx. 250ml) for media refilling and reference standard media. PTWS D620 features independent stirrer speed control for the front and back row of stirrers which can be used as a two 6 vessel format.