other possibilities according to one embodiment the outer halo ring 120 has a plurality of t shaped protrusions 144 that fit into corresponding t shape grooves or indentations 142 on the inner head ring 110 180 the attachment ports between the inner head ring and the outer halo ring may be equally spaced from each other around the perimeter of the rings but need not be according to one embodiment there are six attachment ports equally spaced around the perimeter of the rings for user comfort the inner head ring that fits around a user 39 s head at the level of the forehead may include foam padding 112 covered with a protective material 114 that is easy to clean improves durability and protects the foam for example an artificial leather or u201c pleather u201d is one example of a suitable cover material outside the foam padding the inner head ring may be rigid or may be semi flexible to better conform to the shape of a user 39 s head the inner head ring may be provided in slightly different shapes to better correspond to the actual shapes of different users 39 heads for example some people may have heads with substantially circular cross sections while other people have heads with substantially oval or elliptical cross sections either the inner head ring or the outer.