Canon F1 Eyefinder Beauty Ring

This is a replacement eyefinder beauty ring for the Canon F1 and F1(n). I am not positive if it will fit on a Canon F1N (the model with the front grip).

The ID model screws into the existing threads, it fits snug at 100% and very good at 99%. The OD model slips over the whole silver ring, it fits tight at 100% and slightly loose at 101%.