Attributes . 1-11/16 in-316L Stainless Steel Diaphragm Eliminates Contamination from Diffusion or Outgassing, Designed to 1 x 10-9 cc/sec inboard Helium Leak Rate to Maintain Gas Purity Levels, External Relief Valve is Standard, One-Piece Encapsulated Seat Design with 10 micron Sintered Internal Filter to Protect the PTFE Teflon(R) Seat from Particulate Contamination . Names