Only 25mm and 18mm have been used. Selling as I don’t do much dovetailing :( The shoulderless chisels have gently rounded faces that form an acute angle along the sides of the blade, this design gives excellent clearance right into the corners of a joint. The other advantage of a round back is that it makes the chisels very comfortable to hold in a pinch grip when paring. If you already have Ashley Iles hand ground bevel edged or butt chisels the sides are ground finely enough for dovetailing anyway so these would be a treat rather than a necessity. If you're a woodworker who uses ordinary general purpose bevel edged chisels (bevelled firmers as they are correctly described) then AI dovetail chisels will offer a clear advantage.