These Leybold Ultra Sealing rings fit KF50 (ISO-KF) flanges. The disks are made of aluminum.

Ultra sealing rings and disks are used for sealing small and clamp flange connections for mid to high vacuum. When using an ultra sealing ring, always use an outer support ring.

These ultra sealing rings have a pressure range from 10-8 mbar to 5 bar absolute, tightness to 10-9 mbar l/s, and a bakeout temperature up to 200°C.