●Horizontal fins prevent anchor from turning while screw is put in, Anchor expands and shims the screw ●For use in both hollow walls and concrete, brick, or masonry, Very high ease of use ●Also known as "Bantam" anchors. Kit Include a 100 #10-#12 blue anchors ●1/4" Drill Size. Once anchor installed, they provide a flush, clean appearance in wall. Packaging design may vary. ●Easy to install