Desiccator will not shatter, is strong and light. Will hold vacuum of 754 mm of Hg (29"") for 24 hours. Cold (0°C) does not affect seal. By slowly turning polyethylene plug, vacuum retention valve is operated. Valve takes 1/4"" I.D. tubing. Lower section is polypropylene. Upper section is transparent, unbreakable polycarbonate with a slight tint of amber. Neoprene ‘O’-ring is held by a groove molded into flange of bottom section. Vacuum line attaches to upper half, leaving lower load-carrying section free to be moved. Comes with a perforated polypropylene plate.