... round meter base 100Amps,120~240VAC, Single phase,4 terminal,2 or 3 wire,Fix hub size:1/2",3/ ... 4",1" SYR-100A Series Round meter box description: Item Code No. ... No. of terminalscircuit of applicationapplicable meter form designationMeter class ratingFix hub sizestds packspacking sizeSYR-100A4 ... .Stainless steel sealing ringFix hub size:1/2,3/4,1, meter socket