The FlipToggle® anchor's strong mechanism supplies extra holding power in drywall, plaster or hollow concrete blocks. These anchors are very easy to install and fit in hollow walls up to three inches thick. Also, they are twice as strong as regular toggle bolts of the same diameter. A 1/2" diameter hole is required for installation. Finally, this model is 1/4" x 2 1/2" and sold in packs of 2 units, but FlipToggle® anchors are available in a wide variety of sizes and packages to suit your needs.