The Supertech exhaust valve stem seal for Nissan applications is a 6mm Viton seal sold as a set of eight. Described as an exhaust-side valve stem seal, the part lists the 6mm nominal size and Viton material, intended for replacement use in compatible Nissan engines requiring that seal dimension and material.
Supertech Nissan 6mm Viton Exhaust Valve Stem Seal - Set of 8