Sigg Bottle- Cover Hooks

In the last few months I was a little bit angry about the Covers of my Sigg Bottles. They where all over but not at the place they have to be. So I designed these hooks to hang and find them.
Notice, the diameter of the Circle is optimized for a shelf board with a thickness of 16.1 mm ( something like 0.63 inch).
In the pictures you can see what kind of bottle cover I have mean.