Double Expansion Anchors for Concrete Zinc Alloy 3/8-16 * 3/4" O.D.

Also known as double expansion anchors, these expand from both sides for full contact and a secure hold. To install, tap into a drilled hole with a hammer and position your fixture. Then, insert a screw or threaded rod and tighten. For maximum expansion, the anchor should protrude slightly above the surface before threading the screw. Pull-out strength and shear strength values are 25% of the ultimate values.