1) Any need to add red screwdriver? screwdriver? screwdriver magnetic tools <br><br>2) Specifications: 4mm <br><br>3) When it is difficult to pick up screws? insert a screwdriver into the hole in the middle of the magnetic? so you can easily pick up the screws; <br><br>4) Electric screwdriver? manual screwdriver can be used; <br><br>5) Good steel? magnetic fast? relatively poor no-name tools? because the proportion of steel is less? plus the magnetic effect is sent <br><br>6) The principle is to use the magnet magnetized screwdriver (physical phenomena )