First Infantry Division, Ft. Riley KS, home of the Big Red One. This ring bears the victory standard on one side, Fort Riley Kansas, USA on the other side, and the Big Red One shoulder sleeve insignia (SSI) on the front. This one is scaled to a men's size 13 ring.
Other mens ring sizes can be found here:
Size 9: http://shpws.me/MD1J
Size 10: http://shpws.me/MD1F
Size 11: http://shpws.me/MCKe
Size 12: http://shpws.me/MCJQ