Swing Check Valve Size: 2'' ~ 24'' (DN50 ~ DN 600) Pressure Rating: Class 150 ~ Class 500 Material: WCB, Cast Steel, Stainless Steel THINKTANK is the sole production and R&D institute of Taiwan STONE Company in Mainland China. ThinkTank entered China market in 2002 and separate Shanghai office in 2012. Based on over 30 years experience in researching and manufacturing automatic instruments, bringing in overseas advanced technology and combining domestic users real working situation.