Complete with control knob. Viton® O-rings on PTEF shaft areprotected with precision Teflon® wipers. The plug has a machined-in integral PTEF tip O-ring to make the primary seal. This design providesfor an excellent vacuum tight seal without exposing any material other than Teflon® to chemicals.0-12mm high vacuum plug and control knob(Teflon® O-ring at tip)