The NOSHOK 400 Series Needle Valve is 100% helium leak tested to 1 x 10-4 ml/s for guaranteed performance and reliability. The blow-out proof stem provides a secondary stem seal in the full open position. The 400 Series has a 10,000 psi pressure rating at 200°F. The FKM o-ring seal and PTFE back-up ring below the stem threads protect from corrosion and galling; PTFE or Grafoil packing optional (certain NPT sizes only). All stem threads are rolled for strength and ease of operation.