Reaction tri-block is designed to fit directly on 135mm diameter circular top hot plate stirrers. Versatile design of the tri-block fits 3 of the most common vial sizes on one hot plate: 11Ea- 1 DRAM vials, 11Ea- 2 DRAM vials and 7Ea– 20Ml scintillation vials. Tri-block is hard coat anodized black aluminum.