These barrel swivels are handmade in the USA, and  are used by The Mountain Men Paul Antczak on his wolf line. These swivels measure app. 4 inches long, 1 1/4 inch wide, and the loop's are 1/4 inch thick. The opening of the loop is just over 1/2 inch. Check out his videos here https://www.youtube.com/@montanawolftrapper8666
(If video link doesn't work, copy and paste or check out Paul Antczak on facebook or youtube.)