Some versions of the Strix keyboard come with an extra piece of plastic, similarly undocumented (not in packaging list, not in manual). You use it by removing the M1-M10 macro keys on the left side and you place the cover on the area for aesthetics, if you intend to never use the macro keys.

The Macro Cover function disables M1-M10 keys, as this piece of plastic will permanently press down on the ten keys.

Note that the Fn key becomes unusable if the ten keys are pressed down (probably unintended/bug). This means you can't activate NKRO (or deactivate it if it was on) nor can you adjust the brightness or activate gaming mode. You can still use the multimedia keys though.