Provides separate areas for initial grinding and final homogenization by combining conical and cylindrical surfaces. Adjustable clearance for initial grinding. Material is forced past the cylindrical surfaces when the particle size is reduced sufficiently. Bulb capacities listed represent volumes when the pestle is inserted. Available with ground glass mortar and pestle, or unground glass mortar with Teflon® pestle. When the pestles are Teflon®, the shafts are 1/4"" stainless steel.