We sell two different sauce pan and skillet handles.
Single screw style
The single screw handle was made post 1968. It has a single screw, or, more likely, rivet through the metal part of the handle that holds the handle to the pot. Any size of these handles will fit any pot, so you really can’t go wrong unless you put a small handle on a very large pot or vice versa. The best wy to size this handle is just to measure the overall length of the Bakelite part of the handle.
These were made before 1968 and have a screw at either end of the handle. Note that very early ones has two screws near the front, and another around the hanging hook in the back. If you have one of those, there is no exact replacement.
There are two ways to size these up. The easiest way is to start with the spline height.
If you have a 3/4 in spline, then check the distance between the centers of the holes to determine which handle you have. Alternately, you can just start with that measurement.