They are the remains of a booley hut, a type of seasonal shelter used by families who practised transhumance, the old Irish custom of driving cattle to upland grazing in summer while a small group, usually young women, lived nearby to manage the herd and make dairy produce. The huts they occupied were simple, temporary affairs, and relatively few survive in recognisable form. This one, on the hillside at Knockatassonig, survives better than most.

The main structure is rectangular, measuring roughly 4.4 metres north to south and 3.3 metres east to west, with walls still standing to about 1.1 metres and built to a thickness of 0.75 metres. A wide opening on the south side, nearly 1.5 metres across, served as the entrance, and one of its jambs, the upright stones forming the doorway sides, is still in place. Attached to the north of this building is a larger, slightly less regular addition, broader than it is deep at 7 metres east to west and 4 metres north to south, though its walls have settled lower, surviving to around 0.8 metres. This second enclosure has two openings of its own, one facing north and a wider one at the south-east corner. The thick walls of both structures, up to 1.3 metres in places, suggest they were built to last through repeated seasonal use rather than thrown together for a single summer. At some point the buildings were incorporated into the western boundary of a large, irregularly shaped field, which is probably what kept them standing at all; absorbed into working farmland, they were never entirely abandoned or robbed out for stone elsewhere.