These insertion tapers are for the use of inserting conversion posts or shafts.
One end measures 18g to insert into the post while the other end measures the gauge size of the post.
Available with a 2" or 2-5/8" overall length.
Neometal conversion posts can be found here.
Threadless jewelry is a push pin technology. The removeable end (dark grey) has a slightly curved pin. This pin straightens out when inserted into the shaft (light grey). The resulting spring tension force holds the two pieces together securely.