Not sure which model the one I have is (or was as its a bit bastardised by back yard improver haha). It has a flat across the back as the angle guide not the two vertical rollers and the knife clamp is part of the base, not able to be rotated like the version 3. I actually quite like it for reasons of OCD, the knife support is wider and the stone can be made to travel perpendicular to the entire length of the blade not leaving lines radiating from one point if that makes sense. Looks a bit nicer when sharpened I feel, but just as effective in use. Little bit slower as you have to manually flip the knife over and reclamp it not rotate it clamped...
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