May be marked wrongly in the guidebook as the arete shown looks much harder than 6a. The undercut arete below it is closer to this grade.

ferdia 18/Apr/13 Sent O/S
with Andy
Andy Moles 18/Apr/13 Sent β

Assuming this is the arete below the one marked in the topo, which looks blank and utterly desperate.

with Ferdia
High f6A+
Mid f6A+
Low f6A+
High f6A
Mid f6A
Low f6A
High f5+
Mid f5+
Low f5+