Cosmo Darts – Fit Flight Pro – S-Series – Shape S-4 – Clear. The Fit Flight Pro is the most innovative Flight and Shaft System. Common Flight Shapes are installed by pushing the full flight system onto the shaft, creating a complete unit. These S-Series flights are loosely based on a fantail shape flight, in varying widths. Only to be used with Cosmo Fit Shafts.Cosmo Darts – Fit Flight Pro – S-Series – Shape S-4 – Red. The Fit Flight Pro is the most innovative Flight and Shaft System. Common Flight Shapes are installed by pushing the full flight system onto the shaft, creating a complete unit. These S-Series flights are loosely based on a fantail shape flight, in varying widths. Only to be used with Cosmo Fit Shafts.Cosmo Darts – Fit Flight Pro – S-Series – Shape S-4 – Blue. The Fit Flight Pro is the most innovative Flight and Shaft System. Common Flight Shapes are installed by pushing the full flight system onto the shaft, creating a complete unit. These S-Series flights are loosely based on a fantail shape flight, in varying widths. Only to be used with Cosmo Fit Shafts.