This Ultra Light BioFlex self threading ball is designed to be used on metal bars . It can be usefull for tongue piercing for the bottom ball, or top, to avoid damaging your teeth, but also adapted for all types of piercing where you want to keep your metal bar or banana but want to render you piercing less visible.
This ball is available in different sizes, and you can just screw them onto your existing 1.6mm, 1.2mm and 2.4mm threaded metal bars. The thread will be created inside the ball as you screw the ball on (and will hold strongly !).