Galvanised Through Bolts (Thru Bolt or Wedge Anchor) is a heavy duty mechanical expansion anchor.  The way these anchors work is as you tighten the anchor it draws the tapered end of the bolt into the expander clip forcing it out against the wall of the hole.  Making it a quick and strong fixing.  It can be used on base materials like concrete, cracked concrete, block, rock, brick & stone.  Which enables this fastener to be used in countless applications from residential to commercial.