This as an adaptor to use 50mm ID vacuum / dust extraction hose with a V1 engineering lowrider V3 CNC Makita tool mount (https://www.printables.com/model/167678-makita-700-series-mount-and-removable-dust-shoe-fo)
It slides into the existing Makita tool mount dust shoe that accepts approx. 48mm OD hose. It extends upwards allowing connection of 50mm ID hose. It extends far enough up to prevent the lower cable tie from squashing the hose.
The author marked this model as their own original creation.