If you are familiar with a tractor PTO tiller a flail mower looks very much like that. They have cutters rather than tines and spends much faster. They make them in rough cut and finish cut design. Much depends on the flail cutter head they use. They do not throw debris as bad as a rotary cutter. Have used one a good bit on a boom mower and really liked it. Had one for finish cut and did not like the end result but the cutters they had on it cut at a 45% angle. Boy did the cut look funny. That brand did not have any flat cutting cutters. They are lighter in weight than a same size rotary cutter or the ones I have used are. Another word of caution if considering for finish mowing, you will have resistance to turning with the roller on the ground compared to a RFM and the wheels they use. kt