When the blade grows dull, a tool attached to the bottom of the cutter can be used to snap off the dull part of the blade. To use this tool, hold the cutter by its sides, underneath the clip. Then pull firmly downwards to remove the tool. Insert the cutter blade into the tool's slot, then apply pressure until the dull section of the blade snaps off.
This cutter can also be reconfigured for left-handed use. To do so, remove the blade-snapping tool from the cutter, then slip the slider and the blade out of the cutter. Lift the blade off the slider and reposition it on the slider so the cutting edge is on the opposite side. Put the blade and slider back into the cutter, and then put the blade-snapping tool back on the end of the cutter.