<ul> <li> Alpa System Sterling Silver, Ear Nut. The secure choice for heavy large and precious earrings. </li> </ul> <ul> <li> Similar mechanism to Guardian and La Poussette systems. Sold as a set of 2 pairs. Excellent choice of ear back.  </li> </ul> <ul> <li> <b>Please note that the backs from these do not fit on a regular earring post,like screwback or plain post.Only fit on notched post with 0.75mm～1.0mm.</b></li> </ul>