This is a so-called Clicker ring with a small hinge sitting in one part of the segment, which makes it very easy to open and close.
Titan Highline® is completely nickel-free and suitable for sensitive and very allergic people. It is half as heavy as steel, and is one of the five substances best accepted by the body. It is not actually the titanium itself that is so good for the body, but the layer of titanium oxide that forms on the surface. The oxide layer also acts as a barrier against other substances in the titanium leaking into the body. If the titanium oxide surface wears away, a new layer forms immediately.