The materials of which these fittings are made can be used in the food industry. The brass parts are treated with special nickel - plating according to the NSF®/ANSI 51 standard. The seals are made of FDA-approved FKM/FPM. The threads are cylindrical and under-head O-rings provide a pneumatic seal. This avoids the need for sealants (e.g. Teflon®), which could release solid fragments during screwing and unscrewing that would contaminate the fluid. Our fittings can be screwed and unscrewed any number of times and still remain clean and pneumatically sealed. This choice of materials and treatments make these fittings suitable for use in the chemical, pharmaceutical, medical and electronics industry.