17-4 PH hardened spring stainless steel shaft with 5 (3.5mm high) mini shark fin tabs. An additional welded D-loop provides the ideal location to rig your dyneema shooting line. The first shark fin is located in the middle of the shaft, making it easier to load and power down. The second shark fin is centered in between the first and last 3 shark fins. The rearmost shark fin is welded further back than conventional shafts, providing an additional 5cm/2 inches of rubber stretch. Two wishbones can be overlapped and loaded onto the rearmost shark fin, due to its unique design. The 3.25 inch long, 1.35mm thick, hardened stainless steel offset floppers have a 3/32 inch pin welded on each side to ensure greater reliability and perfect tuning. They are factory certified for straightness. The 8.5mm shaft diameter is perfect for a double roller speargun powered by twin 15 or 16mm small id reactive rubber bands, or any open or enclosed track speargun that accepts euro notched shafts. Tri-cut tip for exceptional penetration and stopping power.