These caps protect the thread in an SP10-38 or SP12-38 installed anchor when it is not in use. After removing the structure that was attached to the anchors, snap one cap into each anchor. The caps are tight fitting and will not dislodge even under vehicular traffic and pedestrians walking over the anchors.
To remove the caps, use a sharp wood chisel. Do not reuse the caps, as they will not longer seat properly once removed.