The centrally disturbed cairn at Pen-y-Groes Isaf measures 18m in diameter and 1.4m high, and is associated with a now lost boundary stone known as "Groes Issa".

(source Os495card; SO09NW2)
RCAHMW AP94-CS 0049-50
RCAHMW AP945004/52, 55
J.Wiles 08.08.02