Carbon seal faces/rings have the smallest friction while combined with any other material: ceramic, silicon carbide.The grades of carbon/graphite are listed as follows: carbon hot pressing,Impregnated Epoxy Resin/M106H, Impregnated Furan Resin/M106K and M120K, Impregnated Phenol Aldehyde Resin F/M106F and M120F and Antimoy carbon M106D and M120D. More detailed information can be found in our web at https://www.china-dongya.com/support/Carbon-Property.html