An Escafil device is the technical term for the "blue morphing cube" that gives a person the power to morph. It goes by other names, but is more commonaly known as the Escafil device, named after the Andalite scientist Escafil, who helped create the morphing technology. It's a light blue cube that is operated by touch contact, and apparently one person, the "giver," who should already have the morphing ability has to touch one side of it, and others, to receive the morphing ability. When touched, it gives the user the permanent ability to acquire DNA from live animals and change ("morph") into the animal. Once the morphing ability is aquired, the Escafil device is no longer needed for it to function.
The morphing technology's exact function is not known, but it is speculated to be a vast network of thousands of microbionic units. These units would be contained in the Escafil device, the central computer for the smaller morphing units.