Vintage Guilloche Octagonal Hanging Compact Small

I think this 2” compact was supposed be concealed in your palm with a chain around your finger or wrist. (I have another listed with the original chain) I left the powder cake inside. I’m not sure what the quarter sized slot is for (not change- nothing to keep it falling out). The other wristlet compact I have has a foil wrapped rouge lozenge in the lid. The guilloche (mechanically engraved repetitive pattern) covers the back and the front has parallel lines over a floral pattern.