Well researched and documented, but quite rare. See Roman Buckles and Military Fittings, p.107-8 "the ring buckle was a 3rd century development due to the fashion of wearing a broad waist belt”. This is a fine example retains its original pin which is rarely found even in museum collections. See British Museum #YORYM-6ECD57 for another example lacking its pin of precisely the same size, 49mm. See also https://www.forumancientcoins.com/numiswiki/view.asp?key=Military%20Belts fourth image for a further example dated3rd century.