It's no secret that Treetools consider the Swiss Istor sharpener to be the best on the market, especially for secateurs and loppers - its hard to believe the Swiss could improve on this fantastic sharpener - but they have!
The Duplex Istor 20 has the traditional Swiss Istor concave composite steel sharpening blade at one end and a diamond grinder at the other (looks very much like to the Felco 903 diamond sharpener with a handle). The diamond sharpener is ideal for sharpening heavier blades like hoes, machetes, lawn mower blades, sickles, spades etc.
The Duplex combines the best of both worlds - this will be the ultimate sharpener - Treetools will list them as soon as they are available.