Suitable For All Size PencilsThe smaller shaving entrance suitable for 6-8mm diameter pencils, the bigger one suitable for 9-12mm diameter pencils^ Portable And QuiteIt is smaller enough to fit in your backpack but powerful to sharpen a variety of pencils. It''s also much quieter than other electric sharpeners^ Multiple Power Sources4x AA batteries(battery not include) or include USB power^ Replace Cutting BladesRemovable cutting blades ,with two additional cutter for replacement.^ Auto & Safety Features Automatically work when plugging the pencil into the shaving entrance. Auto-stop working if finished or the lid is opened. Big shaving entrance cover plate could keep your fingers away from hurt.