The coin measured 1.005 inches (25.5 mm) in diameter and weighed 5.66990 grams.

The bronze coin was made up of 95.5% copper, 3% tin and 1.5% zinc.

This was identical to the British halfpenny as both countries' pounds were pegged until 1979.

The reverse design was by Percy Metcalfe, an English artist.

From 1928 to 1937 the date was split either side of the harp with the name Saorstát Éireann circling around.