High Performance Front Drag Computerized Balance System Multi-stop System Smooth,Silent Transport Systm MODEL RATIO BALL BAERING LINE R9-10F5.1:17+1BB 0.12/150,0.15/120 2/150,4/60 R9-15F 0.15/140,0.18/100 4/90,6/60 R9-20F 0.15/180,0.18/150,0.20/100 4/155,6/110,8/80 R9-30F 0.20/200,0.25/150,0.30/100 6/210,8/170,10/140 R9-40F5.5 : 1 0.30/180,0.35/120,0.40/100 8/220,10/165,12/130 R9-50F 0.35/180,0. ...