High grade, heavy duty rubber construction. Angled strap mounts for comfort and a better transition of power. Spring heel straps w/ easy-grip heel tab. Multiple strap mounting positions for a fine tuned fit. Vented blade to reduce stress while accelerating water over the blade. Generous foot pocket. Sizes: REG = Men's 7-9. XL = Men's 10-12. XXL = Men's 13-15. Power without compromise. The Hollis fin blends graceful movement, power, and bulletproof construction. Meet the new standard in diving.