If you like your chambered cairns obscure, this one's for you. From Canmore:
This Orkney-Cromarty, Polygonal, round chambered cairn, truncated by a field wall, has had almost all the cairn material removed - though an indefinite edge can be traced for about 30 ft. from the chamber on the S. and W.
Nine stones remain of the chamber, whose entrance was in the E, and of these 5 represent what was formerly 3 pairs of transverse slabs spaced 3-5 feet apart and probably indicating a very short passage and ante chamber.
The main chamber, once oval and about 11 ft x 7 1/2 ft, is represented by only 4 slabs 1ft 9ins. to 3 ft. high - rather taller than the transverse slabs.