VERY SMALL. only 1 inch opening and does not seem to open or adjust, once you jam it on, it sits ok, about 6.25 inches inside?

Vintage Bracelet Cuff Modernist Studio Brushed Brass Bronze? Heavy Signed LSE

Unsure material - it is not magnetic and does not test for sterling. 
Really cool

2 inches widest

has a few scuffs as shown which read as dark marks