This is really cool. They fit the 1/4" hole pretty snugly. I used mine on a shelf my wife bought with adjustable shelves. She didn't like the extra adjustment holes so I covered them with these plugs. tight but still slightly raised. I then used the end of a round screwdriver to align them. They almost disappear. Very happy with the results. You don't even see them moving away from the shelves. I highly recommend.