I got a used Ford 907 flail mower about 3 years ago. As the brush I’ve been mowing over the years is changing over to grass the brush hog style mower was leaving a row of cut grass that would at times be very thick. So I found and bought a flail mower. A flail mower has a horizontal drum with cutters on it that spins. This means the cut grass is distributed across the whole width of the cut rather to one side like the brush hog. Well I was missing several flails which meant a narrow strip of uncut grass. So I ordered a whole new set and replaced them.