0-8mm 90 degree high vacuum stopcock that eliminates exposure to corrosive materials. Stopcock can be used to at least 13.6 Kg internal pressure. Ultimate vacuum of 10-7 can be realized with the standard three seals. The smooth acting valve permits fine adjustment of the opening. The front ring seal makes a positive closure against a precision-formed heavy glass seat. The PTFE plug is not bakeable, and the O-rings are not replaceable. Reference marks on the body aid in repetitive setting.