FLX Fit™. Interior textured surface keeps cap in place. Soft stretchy silicone provides optimum comfort. Quick and easy on-and-off design won't snag hair. Latex-free. Introducing Speedo® FLX Fit™, the first silicone swim cap specifically designed for fitness swimmers. FLX Fit™ offers greater elasticity and more comfort that traditional performance caps. The softer silicone compound created for FLX Fit™ Caps offers increased ease of stretch for everything a fitness swimmer needs.