Plain Desiccators are physically the same as Vaccum Desiccator. Only difference is the absence of stop cock. Grease should be applied on the flanges to make it air tight. Both Vaccume & Plain Desiccators are provided with a thick perforated Polypropylene disc with a big hole in the centre for easy lifting. The tiny hles in the disc provide air troughs & support to the diswhes. However procelain discs are advisable in case of incandescent crucibles.