ISO Standard vacuum fitting in size NW10. Used between 2 NW10 flanges and secured with an NW16 clamp. Uses a Buna-N elastomeric O'Ring to make the vacuum seal.Uses NW16 Clamps. 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.