Vacuum Fittings in size NW50/QF50/KF50 and ISO50. This is a modular snap together approach to assembling any vacuum fittings systems. Pumps connecting to just about any equipment. Reusable. Good for use with pumps and systems to 1x10-6 Torr. Industry standard. Leak tight sealing. User can be assured of maximum pump performance and less time chasing higher pressure issues causing systems to under perform.