5 metres east to west, and rising to just over three metres at its northern edge. Into the cairn's western side, someone has quarried down to bare bedrock, removing stones wholesale, and there are further shallow depressions in the south-eastern quadrant where more material has been taken. A concrete cross, erected in 1950, stands in the eastern quadrant. An OS trigonometrical station, a survey marker used for mapping, sits just inside the northern edge, and a telecommunications mast rises ten metres to the north-west. The cairn itself is ancient, though its precise origins are unrecorded; what is recorded is the weight of tradition that once surrounded it.

Knockfeerina, according to folklorist Máire MacNeill writing in 1982, was considered one of the most famous fairy hills in Munster, its name derived from the fairy-king Donn Fi(fada)rinne. The hill was also, in earlier times, the site of a Lughnasa assembly, the pre-Christian harvest festival held in late summer that drew communities together at prominent landscape features across Ireland. Part of that gathering was the custom of visiting the hill at least once a year and adding a stone to the cairn, a practice that would, over generations, have contributed to the mound's considerable bulk. By the time Lynch wrote about the site in his 1909 to 1911 account, however, he noted that all the tradition associated with the cairn appeared to be lost.

The hill lies in County Limerick, near Kilmacow, and the approach is across open mountain pasture, so boots and a weather eye are advisable. The cairn is most legible as a place with a past if you walk around its full circumference; the quarried western face, stripped to bedrock, sits in odd contrast to the accumulated stones elsewhere. The concrete cross of 1950 is the most conspicuous landmark once you reach the summit, though the older structure surrounding it is considerably larger. There is no formal access infrastructure, and the site receives little organised attention, which means the quietness of the place is largely reliable.