GLASS TISSUE GRINDERS ·All-glass construction ·Popular style which affords the choice of hand or motor operation ·Pestle is tooled for an appropriately sized single-hole rubber stopper (not supplied) ·These grinders can be motor-driven at slow speeds by inserting one end of a short metal rod in the stopper and inserting the other end into the motor chuck ·Replacement components are available and completely interchangeable ·Clearance between pestles and tubes is 0.004” to 0.006” ·Manufactured from 33 expansion, low extractable borosilicate glass conforming to USP Type I and ASTM E438, Type I, Class A requirements;