Knife bayonet for use on the 8 mm M1903 Siamese Mauser rifle.
Wood grips held on by rivets with washers.
The characters on the ricasso say "R.S. 121" in Siamese, which represents the year 1903 on the Gregorian (western) Calendar. "R.S. 121" is an abbreviation for Rattanakosin Sok 121. This refers to the 121st year of the Rattanakosin Era, which began with the founding of Bangkok in 1782.