I have multiple pairs of the screw-on ball-style back earrings (star, lightening bolt, and the CZ mini bar) and love them all. They are extremely comfortable and do not dig into my head when I sleep. I have very sensitive ears that tend to react to earrings, but these give me no problems! These are tiny, but that's why I love them - very classic and clean looking. I actually found them fairly easy to get on and I haven't had any issues with them falling off (i double check and turn them once a day). My only complaint is that I have a hard time getting them off - it's probably b/c I tighten them daily, so it was very difficult to loosen them...I actually panicked and thought they were stuck on, but I eventually got them off lol. Lastly, the cz mini bar post is longer than the post for my star and lightening bolt - not sure if that is normal or a defect, so the cz mini bar tends to move around a little more. Overally, I am very happy with them.