Wedge tombs are the most numerous class of megalithic monument in Ireland, built during the late Neolithic and into the early Bronze Age, roughly between 2500 and 2000 BC. They take their name from their characteristic shape: wider and higher at the western end, tapering towards the east. This one at Carrigonirtane follows that pattern faithfully, and with enough of its original fabric intact to make the design legible in a way that more ruined examples rarely allow.

The gallery runs east to west and measures 3.7 metres in length, narrowing from 1.4 metres wide at the western entrance end to 1.1 metres at the eastern close. Three sidestones form the northern wall, four the southern, and a backstone is set into the eastern end. The sidestones themselves decrease in height from west to east, reinforcing the wedge profile that gives these monuments their modern name. Three overlapping roofstones still cover the gallery, and the whole structure is surrounded by closely-set outer walling, which would originally have helped retain a covering cairn or mound, though no clear traces of that mound survive above ground today. The structural detail recorded here draws on the fieldwork of Ruaidhrí de Valera and Seán Ó Nualláin, whose systematic survey of megalithic tombs across the southern counties remains a foundational reference for this type of monument.