Rock anchors are designed for anchoring TallTowers in solid rock. They are constructed of a threaded rod with integral eye and two opposing wedge halves. The anchor is placed in a hole pre-drilled in the rock. Twisting the eye of the anchor forces the wedges against the sides of the hole, locking the anchor in place. Load actually increases the wedging force and develops holding power equal to the full tensile strength of the rod. When anchoring in either bare rock or solid rock covered by soil, rock anchors provide an extremely strong anchor point without the use of concrete. Use the 15" rock anchor when anchoring in exposed solid rock. Reminder: NRG Systems offers its products exclusively to the wind energy industry. Anchors are sold for use with NRG Towers only.