Brass Baffles with Quick Connect or 1/8 inch NPT threads. 15 mm O.D. system connection and 1/8 inch Female NPT gauge tube connection. This baffle will extend the life of your gauge tubes by keeping dust and oil vaports from condensing in the tube. It provides a labyrinth with eight 90 deg. turns between the vacuum system and the tube. The large internal diameters provide fast response and are easy to clean. Note that standard 1/8 inch NPT thermoucouple and Pirani tubes are .403 inch outside diameter. O-ring in quick connect is Buna-N.