Neometal has discontinued this style of threadless end. These are made to fit an old style of threadless compatible labret shafts, exclusively.
They can connect to the 16g labret posts in this listing.
These are for straight pieces of jewelry (barbells or labrets) made by NEOMETAL only.
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.