Plastic desiccator has no vacuum exhaust port or stopcock. Top is made of strong polycarbonate, and bottom consists of polypropylene, with ‘O’-ring seal. Each desiccator comes with a perforated polypropylene plate which is 1/8"" thick and of the proper diameter to rest on the retaining ledge. Desiccator plate has 1/8"" diameter perforations. Plate has a center hole for easy removal.