Picture Hanger Spacer

Four months ago, my daughter had given us a pretty good sized picture frame. The frame weighs a good 15 pounds or so because of panes of glass on both the front & rear. When I tried to hang it on the wall I found that the hanger brackets that came with it were designed for a fastener or hook with a very small & low profile head, like a 18 gauge wire nail, which would not hold this thing very well. In order for me to use drywall anchors and either something more like a #6 pan head screw, I needed