I'm a bit disappointed with these anchors. I did a test outside the wall and it worked great. Not sure if my drywall was too thick or what, but when I used it to hang a shelf, two out of four didn't work. It's almost as if the end of the screw doesn't line up with the back hole to retract the anchor. I've already put the dowel in the wall and when removing it leaves a big hole. Luckily the two that worked were on opposite shelf brackets and I don't plan on putting anything heavy on them! All in all it's not the best!