Unmarked but Australian 1.25". Has covered metal back and horizontal bar pin which is just a hair short of wanting to stay in a closed position. Celluloid has couple of microscopic specks of surface residue across the braid design on the helmet but barely showing. Exc. and only one known to us and is also the button photographed for the book (pg. 175) Button Power by Carter/Hake. Comes w/Hake's COA.