reference: YL-21K15
plug standard: Korea KSC 8305
connector standard: NEMA 5-15R

reference: YL-21K21
plug standard: Korea KSC 8305
connector standard: US NEMA 1-15R or
connector standard: Japan JIS-C 8303

reference: YL-21K22
plug standard: Korea KSC 8305
connector standard: Europlug receptacle

reference: YL-21K35
plug standard: Korea KSC 8305
connector standard: Australia AS/NZS 3112