Can hold vacuum up to 740mmHg for 24 hours without any greasing Autoclavable at 120°C for 15 minutes Top dome, molded in rigid and transparent PC, gives crystal-clear view of sample Knurled knob on top provides easy handling of dome Transparent PC bottom provides increased viewing clarity Internal groove on flange holds silicon rubber O-ring PP stopcock has self-lubricating PTFE plug Three-way plug opens to create vacuum, closes to hold vacuum, and opens again to release vacuum