Screw seals ND8 are made of PP and are supplied without or with fitted septa made of a variety of materials. They have a 8-425 thread, a 5.5 mm centre hole or are closed.

Septa made from Viton have a very high resistance against a wide range of solvents. These septa are highly recommended for use with chlorinated solvents.
Viton septa are not suitable for multiple injections or high injection speeds.