A unique vinyl-plastic compound offers a fast, heatless method for sealing any type capillary tube. Press end of tube into the pliable Critoseal® and twist slightly. Specially formulated vinyl-plastic remains pliable and will not dry out, minimizing leaking and "spin outs." No lead contaminants. Tip-proof tray has 24 numbered duplicate sample slots and contains enough sealer for several hundred tubes.