Caliburn The Key Darts – Soft Tip – 90% – K2 – Natural – 19g. This Caliburn Key Soft Tip Dart features a 90% Tapered tungsten barrel, with a ringed design along the length of the barrel with a milled cut along the rings. This natural look and cut creates a perfect grip that works for many players. They come complete with Caliburn Dart Shafts and Flights. Caliburn The Key Darts – Soft Tip – 90% – K2 – Natural – 20.5g. This Caliburn Key Soft Tip Dart features a 90% Tapered tungsten barrel, with a ringed design along the length of the barrel with a milled cut along the rings. This natural look and cut creates a perfect grip that works for many players. They come complete with Caliburn Dart Shafts and Flights.