This Diafold Single Sided Sharpener is a great, low-cost sharpener for knife and tool edges. Measures 9.375" when opened and only 5" when closed. It has a coarse 325 mesh/45 micron sharpener (as indicated by the blue hinge) to quickly bring back dull edges in preparation for the final edge treatment. It folds up to save space and to protect the sharpener from damage.