... manufacturer of concrete pump pipes and parts in china. Our products include steel pipes, rubber hoses, elbows, bends, reducers, couplings, ... OEM available from us.ZHONGLING concrete pump cleaning ball specification:- sponge balls from 2" to 8", soft, medium or hard ... 5" and 6"- cleaning piston 4", 5" and 6" namerubber sponge cleaning ballsizeDN50 (2inch) soft ,hard ,medium softOD 60mmDN80 (3 inch ...