Product series are distinct by pressure standard, they are C series, M series and R series.
C series: China standard PN1.0MPa and PN1.6MPa + USA standard CL125 and CL150 + International standard PN10 and PN16
M series: USA standard CL125 and CL150
R series: Japan standard 10K and 16K
Note: China standard GB9113.1
USA standard ANSI B16.1 , B16.5
International standard ISO 7005
Japan standard JIS B 2212,2213