... TELE COMUNICATION UNIT O. MODEL NO.-. BOB-180/30-2P ; PLASTIC IMPELLER/ 2POLE-. BOB-190/45-2P, 2S ; STEEL OR ... PLASTIC / 2,4 POLE-. BOB-225/50-2S,4S ; ... STEEL IMPELLER / 2, 4POLE-. BOB-250/50-2S,4S ; STEEL/ ... 2, 4POLE-. BOB-280/50-2S,4S ; STEEL / ...