It measures only about nine metres north to south and thirteen metres east to west, and its bank stands no more than 35 centimetres above the surrounding field on its outer face. Yet the careful geometry of this small enclosure, the deliberate curve of its earthwork, and its relationship to a neighbouring enclosure immediately to the south suggest something intentionally made rather than accidentally formed.

Enclosures of this kind, modest earthen rings defined by a bank and an accompanying fosse (a shallow ditch dug to provide material for the bank), are scattered across the Irish landscape and are generally associated with early medieval settlement and land use, though many remain undated. What makes the Ballyslatteen example slightly unusual is its conjoined arrangement: the fosse on the southern side does double duty, forming at once the boundary of this enclosure and the curving wall of an annexe attached to a second enclosure to the south. The interior of the D-shaped area slopes gently down toward that shared fosse, and a small stream runs along the eastern field boundary, suggesting that proximity to water played a role in choosing this low-lying ground beside the Suir's flood plain.