Channels perform their function without suffering from bumps on rocks, in contrast an external fin could easily flake on rocks and become a rudder that deflects the shot.
The trajectory is characterized by a significantly longer range than conventional spear guns, and a path that remains straight to the end, with no uncontrolled deviations.

The lower portion, the one toward the rod, is hydrodynamic and allows fluid threads to close behind the bow, cooperating in energy conservation and allowing for longer throws.
The glass-filled nylon base ensures superior impact resistance, plus its flat profile ensures good impact on prey and prevents tearing fish flesh.
In practical tests, longitudinal channels proved to be an 'unsuspected resource for being able to line up fish inside those particularly narrow holes where you can barely get the tip of the rifle in.

SPEED INOX spear with Black color Nylon base and 4 tempered stainless steel tips.