This is the C4 Deep Spearo T700 Performance Blades for Freediving and Spearfishing - Blade ONLY Features: MATERIAL: 100% carbon fiber T700 PERFORMANCE BLADE DIMENSION: 869 x 197 mm BLADE HARDNESS: 25 soft - 30 medium - 40 hard WATER RAILS: Constant h10mm FINS WEIGHT: from 600gr. up to 730 gr. A standard stiffness (Tensil Modulus) combined with a 40% higher resistance (compared to the standard) makes T700 High Tensil carbon fiber particularly suitable for more reliable and durable fins. This new line of fins by C4 is manufactured with this T700 composite material. This line of new fins are manufactured with a standard elastic modulus (ability and speed of the material to return to its original position after having been bent) and high resistance (to breakage) carbon fiber. In addition, we have introduced the new large square fabric texture whose fibers are 5 times bigger to improve the performance. The wide bands of the weaving of the T700, compared to traditional carbon fiber cloth, reduce the number of total weaves. Weaves create friction and bend the extremely thin wires of the fiber. Friction and bends, generate negative effects on the performance of the blade. Reducing this effect, by using T700, results in a higher resistance and much better elastic return of the blades, generating more efficiency (more push and less fatigue) when diving.