... :porcelain 2)IEC,ISO9001,ANSI standard 3)Samples avaiable 2012 ceramic pin insulator 56-21) main material:porcelain2) standard: IEC,ISO9001,ANSI3) Samples ... , 56-3, 56-4, 56-56 series6) MAIN DIMENSIONS AND STANDARD PARTICULARS AS FOLLOW TABLE: Class ANSI56-156-256-356-456 ...