Strong and shatterproof with extra heavy walls Flat dome, clear polycarbonate top maximizes interior clearances and provides greater interior volume Large ribbed knob for easy lifting of top Includes 0.32cm (0.125 in.) thick perforated plate Disposable or reusable desiccant can be placed on or under perforated plate Neoprene O-ring ensures tight seal to 0°C without need for grease White polypropylene bottom supports incandescent crucibles on High Heat Minerit HD Ceramic Desiccator Plates