7-11/16"arm 2 15/16" center to center mounting holes. The end hole will need to be drilled out to 1/4" to accept the nylon friction pad. This operator works on most Hehr windows from the 1950s and 1960s used. If you have this same style operator with a shorter arm, it can be cut down and a new hole drilled to make it work.
Application: Airstream and others