This standard specifies the standard parameter table of GB/T 20 1 44-2006/IEC 60399:2002 "Simplified thread for El4 and E27 lampholders with lampshade rings"
GB/T 20144-2006 history
2016GB/T 20144-2016 Barrel thread for lampholders with shade holder ring
2006GB/T 20144-2006 Barrel thread for E14 and E27 Iampholders with shade holder ring