This Victorinox Edge-Mag Magnetic Blade Guard Set includes a 7" protector, 9" protector, 10.5" protector and a 12.5" protector. Open the Edge-Mag and place a knife with the edge aligned to the inside lip with the bolster flush against the tapered end. Close the Edge-Mag like a book and the knife edge should be completely covered. To remove, open carefully like a book, holding the knife by the handle. The Edge-Mag is manufactured with multi poled magnets that cannot magnetize your knife. They utilize complex magnetic fields that alternate every 1/8" and cannot permanently align the poles in any magnetically receptive object.