The largest of the group is an arresting piece of early Christian stonework, standing 1.22 metres tall and 0.62 metres wide, and it carries more decorative detail than its companions. Cut into its face is a ringed cross, a form in which a circle connects the arms, with expanded terminals rendered in false relief, giving the impression of raised carving through careful incision alone. The ring itself is ornamented with rosette patterns, small circular motifs that add a quiet intricacy to what might otherwise read as a plain devotional marker.

What makes this slab especially significant is its inscription, which reads OR DO AEIRECHTANE. The opening formula, OR DO, is an Old Irish shorthand for "a prayer for", a conventional request for intercession found on early medieval stones across Ireland and Scotland. The name that follows, Aeirechtane, is the person being commended to God, almost certainly someone of local importance, though nothing further is known of them. The inscription was recorded by R.A.S. Macalister in his 1949 corpus of Irish inscriptions, the standard reference work for such material, which places this stone within a broader tradition of commemorative slabs produced roughly between the sixth and tenth centuries. The four companion slabs at Ballynakill lack this combination of figural carving and inscription, making this one the most legible record of whoever once gathered here to pray.