The piece the handle sticks out of is 4in. The piece attached to the window is 12in and the diagonal is 8in.
Dave Sr. from SWISCO responded:
September 22, 2015
We don't have an exact match, but look at our 39-002 and 39-021 operators. See if either of these could work on your window. You need to remove the "wood sill cover" to get a good look at your old operator to confirm either will work.