The buttress was built using salvaged stone, and this particular piece, just 63 centimetres long, sits horizontally about 1.4 metres above the lower yard level, which drops roughly a metre beside the outbuilding. Easy enough to walk past without a second glance.

What makes the stone worth pausing over is the quality of its cutting. A jamb is the vertical side-piece of a door or window frame, and this one was finished with a chamfered edge, meaning the corner was cut away at an angle, a decorative and practical technique common in medieval ecclesiastical and civic stonework. The chamfer here has drafted margins, with punch dressing in between, a method by which the mason worked the surface with a pointed tool to create a deliberately textured finish between precise, flat-cut borders. Along the former inner edge of the jamb, four depressions have been cut: two small square recesses near the centre, each about 2.5 centimetres square, and larger rectangular ones at either end, roughly 10 by 5 centimetres. These sockets likely held metal fittings or a wooden fitting of some kind, perhaps part of a hinge assembly or a locking mechanism. The easternmost depression is partially broken off. Where exactly the stone came from is not known, though it is considered likely to have originated in a building somewhere in Cashel, a town whose medieval ecclesiastical complex, including the famous Rock, generated considerable dressed stonework over the centuries, some of which has ended up scattered and repurposed across the surrounding area.