I have a 20" drum 4 roller, dual eddy current chassis dyno. It was one of several that were built about 15 years ago at a cost of over $50,000. The two pairs of rollers are connected by a 4" Gilmer belt. The dyno can be moved around as it has a built-in hydraulic system that raises it above the ground so that it can roll on castor tires. The overall length of the dyno cabinet is 12 ft. The pair of drums are close enough together that a dragster can go on this dyno and wide enough that a dually pickup can sit on it. The outside of the drums are machined perfectly round and then knurled for traction. You can turn one drum over and it is machined so accurately that inertia will continue to turn it over for a couple of revolutions. I have had this dyno for a number of years, but never found a good place to install it, so am now selling or trading it for street rod, pick up or reasonable offer. I will put it on my equipment trailer and deliver a reasonable distance or meet you somewhere. This, however, is a heavy piece of equipment. This chassis dyno makes the kind of impression that will make people want to put their high horsepower cars on it. If you've ever thought about owning a chassis dyno (and not one of those little ones) that can generate you some big income, here's your chance! I will FaceTime with you so you can get an accurate view of it. Call for details.