The music box has an extra long cord (can of course be shortened to fit) for sewing in.
The cord ends with a pull disc, a so-called "cake handle". The pull piece shown (the coin to pull/cake handle) is supplied loose and prevents swallowing. The cord is fed through the smaller hole in the pull disc and knotted at the bottom at the correct length. The knot can then be pulled back through the larger hole to create an (invisible) knot.
