This is a grain mill. It's designed to work as an accessory for a kitchen-aid style stand-up mixer such as this one: https://goodrobot.com/bots/265 For those wondering what materials this can be used to mill: https://pleasanthillgrain.com/family-grain-mill-info
Here is the user guide: https://www.everythingkitchens.com/media/pdf/FGM-manual.pdf
Thanks to Joseph for the donation of this fine grain mill!
Purpose: to mill grains.