We use a Case IH 8610 which I believe is identical to the BP 25 Hesston. It will grind up 5x6 roundbales at pretty much any length of cut. This is adjustable. Book says 85 hp is sufficient to run, but I would run at least a 125 horse tractor on it. It is an easy to maintain piece of equipment. In 7 years of use the only main thing to break was one of the bearings on the rotor. It does a good job for us but it is not as heavy duty as a Haybuster .