Since May 2015 at Handworks 2015 where I introduced the Sterling Dovetail Square, I have been asked if the Dovetail Blade will fit in the Starrett 4inch Square. For unknown reasons Starrett makes thier 4″ squares with blades that are .018″ thinner than virtually every other square maker.
I have been keeping a tally of how many people wanted Dovetail Rules for their Starrett squares and in April 2017 I completed a run of DTR-2 units specially designed for 4 inch Starrett Squares. Note that the DTR-2 will fit Starrett 4″ Double squares and 4″ Combination Squares. The dimensions of the Sterling Dovetail Rule DTR-2 are: 4″ long, by .300″ tall on the taller end, .90″ on the smaller end and .064″ thick!
You can purchase the DTR-2 here.