The Prentice/Epsilon line of knuckleboom self-loaders is available in two models: the standard L-boom and the Z-boom, which folds to save space on the trailer. Various lift capacities and operational speeds are available for each model. Featuring a standard 22-ft boom and 2962-lb lift capacity at full reach, the Prentice 2124 self-loader is also still available. Caterpillar Forest Products. 800-368-6029.