That pairing is, in itself, unusual for early medieval Irish memorial practice, and neither of the individuals named has ever been identified.

The slab, described in detail by Harold Leask in 1950, is substantial: roughly 2.2 metres long and a metre wide at the head, tapering slightly toward the foot. It is broken in two and considerably weathered, which is unsurprising for an outdoor granite monument of considerable age. Within a single-line border, the carving presents a cross formed from a continuous interlaced band, a technique that produces triquetras, three-cornered knotwork motifs, at the ends of each arm, and more complex derived knots at the head and base where an extra loop has been added. The centre of the cross opens into a circular expansion filled with four simple knots running on a single band. In the two upper quadrants are circles enclosing Greek crosses, one with curved expansions at its centre and ends, the other with angular ones. The lower quadrants carry the inscriptions: "Or do Maccois" and "Or do Diarmait", meaning "a prayer for Mac Cois" and "a prayer for Diarmait". The formula "or do", an Old Irish phrase requesting a prayer on behalf of the named person, appears frequently on early Irish memorial stones, usually for one individual. Here it appears twice, which is what makes the slab stand out among comparable monuments.

The slab forms part of the exhibition display at the Glendalough Visitor Centre, where it has been on show since at least 2005. A detailed drawing of it was published by Robert Cochrane in a set of historical and descriptive notes on the ecclesiastical remains at Glendalough, produced as part of the Eightieth Annual Report of the Commissioners of Public Works in Ireland, issued in Dublin in 1925. A three-dimensional digital model of the slab was subsequently created by The Discovery Programme, making the interlace carving considerably easier to read than the weathered stone surface alone allows.