Quietsharp 6 Classroom Electric Pencil Sharpener, Ac-Powered, 6.13 X 10.69 X 9, BlueSuper duty motor with thermal overload protection keeps the plug-in sharpener from overheating. Sharpen a high volume of pencils back-to-back without a break.Tamper-proof safety switch shuts down the motor when large shavings bin is removed, the Bostitch standard for safety in a classroom environment.Tip Saver Technology prevents over sharpening and extends pencil life. The cutters pull back once the pencil is completely sharp, even if the student doesn’t retract the pencil.