Magic goes in... Mundane comes out
A typical Purple Bag of Magic Nullification is two feet square, with an opening which would negate any item that could fit in its opening.
These items are rare, but are created for use by the Explorer’s Society to destroy cursed and unwanted magic items. Note that many artifacts are immune to the bag’s effects, or will merely be neutralized while inside the bag. Such items return to full functionality once removed.