According to Coflein (J.Wiles 27.08.02) this is:
“A prominently situated barrow, 18m in diameter and 1.5m high.”
I had intended to visit on 8/9/19 following an ascent of Great Rhos from Cwm Farm; however, I found that outing required everything I had in the energy tank.... no reserves. One for the future, perhaps.