We use the Single/Double in several of out facilites around the United States and our operators love them. It cuts the unload and load time down tremdously and we do store product in racking in several of our locations. As for operation, it is very easy to use and the training we have is a very nice video/manual/hands on program. I have never heard it called Double Fork, so I hope that we are talking about the same unit. Ours are attachments that can have the 4 forks closed and utilized as a regular fork, or they can be expanded with the hydraulic controls and becomes 4 forks capable of picking up 2 pallets side by side.