Here is a little more info on the Multivator and what they do.  Ken Sweet
 "The Multivator is a high clearance rotary tillage machine designed for 
inter-row cultivation of garden, truck, vegetable, fruit, nursery, strawberry and field crops. Controls weeds, improve soil conditions, and reduce your dependence on herbicides. 
There are Multivator models to suit every individual's needs from 1 row to 6 
row configurations with tractor requirements ranging from 15-150hp. Optional equipment can also be added to your Multivator such as fertilizer hopper, ridger 
assemblies, and a steering guide. The light duty FL, medium duty FP, and the 
heavy duty FPSR machines are all available in high clearance as well. The FL 
is designed primarily to suit tractors between 15 and 50 hp in light soil 
conditions. The FP is suitable for 25 to 100hp and average soil conditions 
while the FPSR it designed for 50 to 150hp in heavy soil. The FPSR is also 
widely used as a strip tiller."