BEWARE! [SEP] Delivered quickly, these are terrific at keeping my studs firmly in place.  I use them on my screw back diamonds.  Bonus is the backs measure about 10mm, so they address the dreaded &#34;earring droop&#34;.  However, I placed the second pair (comes with 2 sets) on my secondary piercing studs, which have a small indentation at the end of the posts. They are now stuck on!  So, a helpful product, but BEWARE.