High Speed Back-twisting Machine 1,For CAT5E,CAT6,CAT7 2,Motorized ... 120mm,3+3 ditch,pecision potentionmeterPay-off deviceAccumulative type tension sensor stand,inked with pay-off motor,ensure constant tension in ... with constant tansion HR-DB-500/630(bobbin size) High Speed Pair Back-twisting Machine