Simon - There were 12 different type 30 bayonet manufacturers and in "my book" about 6 major variants, however ... you can find 30 variations if you go by Raymond Labar's superb book (Bayonets of Japan), which is probably THE book to own if you ever get into collecting them seriously. The curved quillion is actually pre WW2 (1930s) manufacture. During the war, they went to straight ....and as the war progressed, more corners were cut with respect to handle shape, blade quality, screws used, etc... I like to collect sample small arms pieces of Imperial Japan, and since I had a few of these , I wanted a way to easily display them on the wall. Thanks for the note! Dan