What makes Ballincraheen unusual is not simply the enclosure's scale, roughly 72 metres by 66 metres in a broadly rectangular form, but an additional feature projecting from its northern corner: a wide, semi-circular earthen bank that curves back inward towards the north-west, creating a kind of annexe or forecourt arrangement whose purpose is not immediately obvious. The incurved front of this secondary bank sits about 12 metres from the main north-west wall of the enclosure, and the whole structure has the feel of something carefully planned rather than accumulated.

Enclosures of this general type, defined by earthen banks rather than stone, are a familiar feature of the Irish early medieval landscape, often associated with settlement, agriculture, or the demarcation of status. The main bank at Ballincraheen is substantial in places, reaching an external height of 1.75 metres on the north-east side with a base width of 6.5 metres, though it is lower and narrower elsewhere. Perhaps the most intriguing detail, reported by the landowner Mr Stack, is the former presence of a souterrain beneath the south-west sector of the interior. A souterrain is an underground stone-lined passage, typically associated with early medieval ringforts and used for storage or refuge. No surface trace of it could be found at the time of survey, meaning it may have collapsed or been filled in over the centuries. The enclosure and its lost underground passage were documented in C. Toal's North Kerry Archaeological Survey, published in 1995.