EM121N-TM, XX121X-TM(The "X" in "XX" stands for A-Z, representing
different series and different display ratio codes. These differences have no
effect on safety performance)
IEC 62321-1:2013 IEC 62321-3-1:2013
IEC 62321-4:2017 IEC 62321-5:2013
IEC 62321:6-2015 IEC 62321-7-1:2015
IEC 62321-7-2:2017 IEC 62321-8:2017