Caliburn Spiro Darts – Steel Tip – 90% Tungsten – S2 – 24g. Each pack contains 90% tungsten barrels fitted with Caliburn replaceable points, stems and flights. Thread: 2baCaliburn Spiro Darts – Steel Tip – 90% Tungsten – S2 – 22g. Each pack contains 90% tungsten barrels fitted with Caliburn replaceable points, stems and flights. Thread: 2ba Supplied fitted with the Caliburn Replaceable Point System.