The space saving design of the desiccator dome provides maximum interior clearances. They provide an average of 13% greater interior volume than standard hemispherical domes. Clear polycarbonate top and white polypropylene bottom. This strong, shatterproof desiccator will hold a full vacuum (29.9" Hg [759mm]) at room temperature for 24 hours and will remain air tight even if not under vacuum. A polypropylene stopcock with a PTFE TFR plug which turns, allowing a slow, gentle entrance of air preventing unnecessary turbulence and crucible damage. The stopcock handle is a highly visible red and has a port that accepts 1/4" (6.4mm) I.D. tubing. Lid has a neoprene O-ring seal that does not require grease, but is not harmed if grease is used. This item is supplied with a polypropylene plate 1/8" thick with 1/8" diameter perforations for air transfer. The plate rests on the retaining ledge of the bottom section and has a center hole for easy removal.