Review on Ansoon Self Drilling Drywall Anchors Together Fasteners by Adolfo Goins

I'm buying these to hang some small bookshelves. In short, these are the worst wall anchors I've ever used. I tried the first two hangers with self tapping screws but I couldn't get them. I decided to pre-drill the holes to bypass the self-tapping feature. After pre-drilling the holes, I attempted to insert the wall anchors with a cordless drill and quickly removed the heads from the hangers. Then I had to remove them with channel locks. I tried installing two more with a good old screwdriver only to loosen the heads back into the same holes in the wall. Now I run to the hardware store to buy wall hangers that fit.