This Royal Dublin Fusilier button set most likely came from the pockets and epaulets of an officer’s service dress tunic.
As regards size, they are all approx 18mms in diameter. All the buttons could benefit from a good clean as the brass now has a dark patina. The buttons show signs of service wear and several have dents in them.
This set would be ideal for display purposes or for restoring an R.D.F. officer’s tunic. They date from between 1902 -1922.