Keyboard spring anchor strip (K3111-1/2) for Monroe K-series calculators

This is a keyboard anchor strip for Monroe K- or KA-series mechanical calculators, which were manufactured between 1920 and 1928. It is used to attach springs to. The other end of the springs go to locking shutters which lock the keys in place.
In the M-series, this is part number 3111-1/2, so let's call this part number K3111-1/2.