If you are sharpening very large blades, you may want to choose to use the larger flip over blade holder.

Also some folks will modify the 4 inch flip over, that come with the system, to accommodate the blades that are shorter than 4 inches and would like to retain the ability to sharpen the larger blades as well.

It is very simple to grind the 4 inch flip over holder to accommodate the smaller blades and will extend the usage of the Blade Sharpener.