ISO Standard vacuum fitting in size NW16. Used to adapt an NW16 flange to an NW10 flange and secured with an NW16 clamp. Uses a Viton elastomeric O'Ring to make the vacuum seal. Compatible with NW, KF, QF and ISO standards. Manufactured generally in the USA. Some exceptions apply. This is a building block approach for creating and supporting vacuum systems to 10-6 Torr.