TIHI021-5Internally Threaded Basic Circular Barbells Navel Jewelry / Belly Button Ring – Titanium. Counter Sunk Balls are solid and one piece. Both ends are removable and thread off. Manufactured from High Polish Implant Grade Titanium (Ti-6AL-4V-ELI ASTM F136). Our internally threaded circular barbells are an essential tool in any piercer's box - and a versatile piece of jewelry that can be worn in many different piercings. Choose from a selection of gauges, widths, and either a 3mm, 4mm, 5mm & 6mm ball size.▸ We are transitioning our material to Japanese Titanium. Several of the colors/sizes have been updated already to Japanese Titanium.