Casement window cranks

Thanks for posting. I am confident we can help, but I need a better view of the operator. Can you show it to us from a bird's eye perspective, with the window open and the arm profile totally clear? That's the best way to narrow this down. Many thanks. 

Thank you! These photos are a huge help. My top suggestion would be the 39-221B. This appears to be a match for the original hardware, but look it over and see what you think.

Note that the cover and handle are sold separately under the 39-451.

detail of 39-221B