You want locking backs?  These are the ones!!!  I've had 2 pair of these backs and they both work perfectly!!  Never lose an earring again!!!  Just be careful when you are taking them off.  The back are hard to grip when you are removing so just hold on tight and do it in a place where if it drops you will be able to find it.  I dropped one, hence the second pair of backs.  Found the missing one a few weeks later.  ANYTHING for peach of mind with diamond studs!!!!!!!!!