The middle one measures around 24 metres across, its enclosing bank rising only 0.4 metres at its highest and 0.6 metres wide, barely distinguishable from the surrounding ground to an untrained eye. Nobody knows what they were for.

The three enclosures are spaced roughly 130 to 174 metres apart along a northeast-southwest alignment, close to the raised embankment of the former Galway to Clifden railway line, which closed in the early twentieth century. Their construction entirely from a low bog bank, with no stone or timber, is unusual, and their purpose remains unresolved. They appear on the 1898 resurvey of the Ordnance Survey six-inch map but are absent from earlier editions, suggesting they are relatively recent features rather than ancient ones. About 377 metres to the northwest lies the ruin of Munga Lodge, and a tentative connection has been proposed between the lodge and the enclosures, though the nature of any such relationship is speculative. They may have served some agricultural or estate function, or they may have marked boundaries, but no firm evidence points either way.

All three rings are clearly visible on aerial imagery, which is perhaps the best way to appreciate their geometry and their curious alignment. On the ground, the low banks are subtle enough that the site rewards patience and a good eye for slight changes in the bog surface.