Designed for 6 rows of wide spaced P3 bars set parallel to the rotor centerline cross section (mounted flat). Diameter - 25". We've never installed or required a reverse bar, and replace the discharge paddles with shortened rotor bars. RPM required for feed_carry thru of crop_MOG is much less than with std. rotor or CDF. This is due to diameter of the drum, and use of the leading edges of the bar teeth allowed by flat mounting style. Another operator observed my previous post and invites calls, as well. loren lauck of Bloomfield, NE (402)373-4367 cell -- (402) 841-5236. Thanks, loren.