these are great!  I no longer wear  4gauge plugs, because I got tired of the weight of them, and want to sometimes wear regular small studs but it's hard to fit regular earrings over the enlarged hole in my lobes.  I got ball studs that are bigger than the piercing opening, but the regular backings just come through, so I replaced the backings with these grip-backs, which stay on tightly even if I wear them for days, showering and sleeping and all.  Great on regular-thickness posts, and they slide on as far as you want.  They do not accomodate thicker posts.