Naked Viking Surf: Mannkine Thruster - Medium (Twin Tab) The Dan Mann designed Mannkine fins are part of the NVS Apex Series lineup. Dan designed these to complement his board designs, whether they are shaped by him or produced by FireWire. DETAILS: Front Base: 4.43 inch Height: 4.47 inch Rake: 34.3 Degrees Area: 15.00 inch Foil: Flat Center Base: 4.32 inch Height: 4.35 inch Rake: 34.3 Degrees Area: 14.22 inch Foil: 50/50