OS&Y Construction,Bolted Bonnet, Welded Bonnet & Pressure Sealed BonnetBack-seating, Renewable Seat RingFull Port / Conventional Port. Size: 1/4 - 4″NB. Material: A105, F304,F316 or Equivalent, Available also in low temperature steels, low alloy steels, stainless steels,duplex type stainless steels and other exotic materials; Various trim materials available to suit service conditions.