What makes it worth a second look is not its size, though at roughly 1.85 metres long it is a substantial piece of mica schist, a metamorphic rock with a faintly glittering, layered surface. It is the name attached to it. This is traditionally known as the horse-dealer's grave, a designation that sits oddly among the early Christian saints and scholars with whom Glendalough is more commonly associated.

Patrick Healy, writing in an unpublished OPW survey of Glendalough's ancient monuments in 1972, recorded the slab in some detail. The face is smooth and slightly concave, and there are two perforations cut through the stone: a larger oval measuring roughly 0.2 metres by 0.16 metres near one end, and a considerably smaller opening, about 0.07 metres by 0.03 metres, near the other. These kinds of perforated slabs appear occasionally in Irish early medieval burial contexts, though their precise purpose is not fully understood. Healy noted that the slab was already recumbent and overgrown at the time of his survey, with only the area around the larger hole visible above the surface, and that no inscription of any kind could be made out on the stone. The folk name offers no obvious explanation. Whether the person buried here was actually involved in the horse trade, or whether the name attached itself through some other local association now lost, is not recorded anywhere.