Unbreakable PolyBoard™ base guaranteed for a lifetime of use. * Self-sharpening stainless steel blades cut up to 10 sheets at once * Permanent 1/4" grid and dual English and metric rulers * Patented automatic blade latch locks with every cutting motion * Torsion spring prevents blade from accidentally falling during operation * Manufacturer"s limited lifetime warranty (includes blade) * Non-skid rubber feet