S-990 Firestone Fins

S-990 Firestone Fins in 100% Carbon - 200 Line C4

The S-990 Firestone are an advanced solution for freediving and spearfishing, made from 100% carbon and part of C4’s 200 line, designed to deliver an optimal combination of lightness, responsiveness, and mechanical strength.

Structure and Materials

The blade features a progressive lamination of 4 different types of Japanese carbon, arranged in 7 unidirectional layers. This technical construction allows for excellent optimization of thrust transmission and blade durability.

The blade tip is shaped with a swallowtail profile, a design that improves finning fluidity and hydrodynamics, reducing water resistance during freediving movement.

Water Rails and Protection

The water rails are integrated through bonding and high-pressure, high-temperature overmolding, a process that fuses the polymer with the blade’s carbon composite, eliminating the risk of detachment during dives.

The variable geometry of the water rails has been engineered to:

• Protect the blade in the area adjacent to the foot
• Minimize load losses along the entire length of the blade

Foot Pocket and Sizes

The fins are fitted with the 200 foot pocket, made with a black thermoplastic elastomer upper and a red polypropylene sole, designed to ensure comfort, fit, and durability in the water.

The blade dimensions are 770 x 192 mm, optimized to ensure efficiency and control during finning.

Stiffnesses and Available Sizes

The S-990 Firestone fins are available in three stiffness levels to suit different thrust and control needs in freediving:

• 25 Soft
• 30 Medium
• 40 Hard

The sizes cover a wide range:

• 36/37
• 38/39
• 40/41
• 41/42
• 42/43
• 43/44
• 44/45