Lee Valley: 70M46.50
Sub-micron carbide particles in this sharpener are about one-fortieth the diameter of a human hair and are the kind used in the most demanding of metal-machining processes.
Extremely hard and durable, the carbide can be ground to a much keener and more durable edge than common carbides. Each of the two blades has four edges and can be rotated to a new edge if one is accidentally damaged.
The sharpener comes as a right-handed version but the blades are easily reversed to convert it for left-handed use.
To sharpen a knife you just draw it through the intersecting carbide blades with light pressure. A very dull knife may initially require several light passes but can be maintained thereafter with a single pass for touch-ups.
Not only is it easy to use, but if used with care, it should last for as long as you (or we) live.