The electric leaf shredders look much like a open ended barrel with a string trimmer inside. They are perfect for yardeners faced with mounds of leaves to dispose of in the fall. These tools handle only leaves and will not work to chop up twigs and branches. When the leaves are dry, it is almost impossible to overload this machine. You can feed those leaves in as fast as you can and it just chops them up into confetti-sized pieces. When leaves are wet, you need to feed them into the machine more slowly.
There is usually an adjustable shredding screen below the fiberglass trimmer lines doing the cutting. You can set the machine on top of a trash can, catch the leaves in a plastic bag attached to the bottom, or just let the chopped leaves fall to the ground in a nice neat pile. You can also process pine needles, grass clippings and thatch. While this machine is much safer to use than a gasoline driven chipper shredder, you should always wear gloves and safety glasses.