Niobium Circular Barbells with 3/16" surgical steel balls are available in 3/8" and 1/2" sizes in both 16 and 14 gauge, and 5/8" in 14 gauge. Available in Niobium Blue, Niobium Green, Niobium Purple, Niobium Purple, Niobium Rainbow, Niobium Shiny Black or Niobium Teal.