This style bayonet first made its appearance as the Belgian M1953 Export Bayonet
for the NATO FN FAL 7.62 caliber auto rifles. These were originally equipped
with metal grips. The second variant - used by the Belgians - was equipped with
wood grips (also exported to British Commonwealth countries). A third variant -
with metal grips but without the flash-hider "ears" - was used in trials (but not adopted) by the USA.
This fourth variant has ribbed-plastic grips and is Parkerized. It is believed
these were exported to Portugal (and perhaps some South American countries).
All these bayonets attach to some variant of the Belgian FN-FAL
(Fabrique Nacionale - Fusil Automatique Legere) Infantry Rifle.