... is a mannufacture specially produce the o-ring,x-ring. Material are :FFKM,NBR, HNBR,EPDM,SI,FKM(VITON)CR,PU ... ,PTFE,ACR(A) 1. material:NBR,EPDM,SI,FKM(V270M),CR,SBR,IIR,HNBR,ACM ... . Colour: red ,white,black ,blue ,yellow,green ,brown ,etc.7. Standard:AS568,DIN3771,JIS B2401,ISO3601,BS1806.8. accept sample or ... requirement ,but o-ring's mold fee is free. KTW standard rubber seal