Trimmer offers a virtually unbreakable molded base, ergonomic soft-grip handle and nonskid feet. Self-sharpening, stainless steel blades accurately cut up to 10 sheets of paper. Patented, automatic blade latch locks with every cutting motion. Permanent, 1/4" measuring grid on trimmer won"t wear out like painted grids. Imperial/metric ruler ensures proper alignment. Torsion spring keeps blade from accidentally falling. The finger guard protects the entire blade length.PREP218X. P218X. Martin Yale Martin Yale Premier PolyBoard Trimmer.