... three types: CHYS-XB-X, CHYS-XC-X, and CHYS-XD-X. Detail as follow: (1). CHYS-XB--X type have CHYS-2B-6 ... to "12" ,"24","36"or more.(2). CHYS-XC-X type have CHYS-2C-6,CHYS-2C-12,CHYS-2C-24 ... CHYS-XD-X is same as CHYS-XC-X, the only different just is usually CHYS-XC-X type use CFZY series ... ozone generator, and CHYS-XD-X type used CFK series ozone generator. ...