Carton Opener from Midori.

Compact, easy-to-use cutter specifically designed to open boxes and cartons. Unfold the casing to reveal the small blade, which is ceramic and replaceable. Press the straight edge of the casing down on paper to cut just a single sheet of paper safely. When slicing through tape, hold at a slight angle, to give more depth.

The casing is magnetic, so can be attached to fridges, filing cabinets and toolboxes etc, to be on hand when needed. Casing diameter 45mm.