The shaft has been truncated by the break, and so the geometry that would answer the question simply no longer exists in the stone.

The slab originally came from High Island, a remote monastic site off the Connemara coast, where it was uncovered during excavations of the floor of what researchers call Cell B, a clochan associated with the island's early medieval monastery. A clochan is a small, corbelled stone hut of the kind used by early Christian monks as individual cells or oratories, typically drystone-built and beehive-shaped. The slab was found in relation to the clochan lying to the east of the main church on the island. It measures 36 centimetres in height, 44 centimetres in width, and 6 centimetres in thickness, and only one of its faces bears any decoration. Fisher, writing in 2014, recorded it as item number 30 in a catalogue of such material, noting the ambiguity introduced by the truncation. The garnet mica-schist from which it is cut is a metamorphic rock with a faintly glittering surface, and its use suggests the carver worked with locally available material rather than anything brought in from elsewhere.