To keep it upright the mast has tensioned guy wires attached, usually in sets of 3 at 120° angles, which are anchored to the ground usually with concrete anchors. Multiple sets of guys (from 2 to 5) at different levels are used to make the tower rigid against buckling. The guy lines have strain insulators (Johnny balls) inserted, usually at the top near the attachment point to the mast, to insulate the conductive cable from the mast, preventing the high voltage on the tower from reaching the ground.