When selecting, it is generally best to purchase knife blocks with horizontal slots so the knives being stored are not resting on their sharpened blades but instead are resting on their sides. Vertical slots have a tendency to dull blades as a knife is drawn out or returned to the slot if the vertical movement draws the blade against the solid block. Some blocks may be designed to hold only knives while others may have slots for holding a sharpening steel and a set of kitchen shears.