Take the western road up Glen Prosen, past Bykenhillock (I note this now has an anglicised plaque reading 'Beacon Hillock' - obviously not locals...) to the turning for Muir of Pearsie Lodge. Park carefully so as not to block the entrance on the west, and take this track, following it for about a mile (and through a red gate) till you see the stones on the south side of the track.
This is a strange little site. The eastern group may be a four-poster or the remains of a circle - I'm not sure. There are four stones, but all at irregular intervals, two being quite large and two rather smaller. The two western stones, however, would have been quite spectacular when upright, being nearly 8 feet in length. Unfortunately, they are both now prostrate.
There are no noticeable markings on any of the stones.