Niobium is a high quality metal right along side Titanium! It is a softer metal, making it much easier to use as captive hoops need to be bent to put in and out. It is safe for people with metal allergies and sensitivies. These annealed Niobium Captive Bead Rins come with Titanium beads. 16 gauge 8mm comes with 3mm bead. 16 gauge 10mm, 14 gauge 8mm and 10mm come with 4mm beads. Dont want just a plain silver bead? Search "captive bead" for more options!