Main description in Hatterrall Hill 1
2-3m directly east of cairn - please replace exactly as found. From here continue head over to the Offa's Dyke and follow it southwards to continue the walk. (Or you could go half a mile north along the ridge to grab GCZQZM - Sid and Bob's 'Along the Border' cache and then come back and continue the walk).
Many thanks to the Brecon Beacons National Park Authority for giving permission for these caches.