4 footer I was cutting brush and plentiflora Rose's over my head while seated on the tractor with no problems in 4 low. The areas that were BlackBerry briers were smooth and easy. The Rose's bogged it down on occasion.
I have an rk24 with a 60” brush hog. Not sure what brand but it was not RK by KK, it was a heavy duty green colored model. Works fine for clear brush and small trees.