Hi - Our Ninja blender had a small piece of plastic snap off that rendered it useless. The piece was a trigger for the mechanism to make sure the lid was in place/ aligned. This little ring holds a new trigger piece so that you can use your blender even if the piece snapped on yours. This blender is probably 10 years old, so it might not work for newer ones. Enjoy!

Also, the height is probably 1mm more than it needs and the blender top is canted a bit but it works and that's really all I wanted.