All Deep Apnea S-Glass blades are manufactured with 100% S-Glass Fiber. The chemical formulation of S-glass differs from the standard Fiberglass. S-glass is 30% stronger and 15% stiffer and lighter than Fiberglass and retains these properties up to 1500° F. S-glass is also considerably tougher than Fiberglass; there are not comparison between those two in terms of stiffness and performance. When the application is for a Freediving fin the weight is a factor too, S-Glass Fins and lighter than Fiberglass Fins and also the response of the S-Glass Fins compare to the Carbon Fiber ones.,,The S-Glass Fins are manufactured following the same formulation proprietary of Deep Apnea has for the Carbon Fiber where the Multilayer disposition of the fibers inside of the core creates a "Variable Parabolic Stiffness" (VPS), resulting in a faster blade response. This delivers a comfortable surface swim and also a strong ascend, with considerable less effort, which in turn saves oxygen during each dive.,,The S-Glass Fiber Fins comes with 2 years warranty.,,The S-Glass blade Black Grouper Edition is 85cm long and 20cm wide. The side T shape rails are just 1cm tall reducing the weight on the tip of the fin. This Fins compare to a normal Fiber Glass fins has a better performance because of the S-Glass. This fins and can be use for Freediving, Spearfishing at any depth.