This DRDII comes in a gear-reduced model. Gear reduction means you turn the wheel more times but each turn is easier to make, therefore you can put more clay through at a time. The "feed" side of the table is shorter and lower. Slab rollers with gear reduction should only be rolled in one direction.
The Reverse Threaded Handle Adapter has a ratchet to prevent reverse handle travel which prevents mechanical damage to the machine due to abuse.