An array for use with a surgical navigation system is provided. The array comprises a frame and first, second and third markers attached to the frame. The first, second and third markers are detectable by a tracking system used in image guided surgery, and the first marker is movable relative to the frame. In one embodiment, at least one marker slides along the frame from a first position where it is held in place to a second position where it is also held in place. In another embodiment, one or more of the markers is removed from the frame at a first position and reattached to the frame at a second position. In still another embodiment, a portion of the frame itself moves with the movable marker.