Dual arm window operator made by Anderson Window Company arms 10 1/2 inches long,
A quick learner from Eau Claire WI says:
September 3, 2015
The window operators were installed in the late 70s
Tom from SWISCO responded:
September 4, 2015
Thanks for posting. This looks like our 39-390. Check it out and let me know if you think this can work as a replacement.