Made with 3 materials in the Cutter of Thermoplastic Rubber. The unique formula has Enhanced Geometries to obtain the very best Effort/Performance Ratio. This Non-Vented Blade Fin has a Soft and Comfortable Foot Wallet for hrs of Snorkeling Fun. The Open-Toe Creation enables a bigger selection of foot sizes. The Cutter of the Fin has Side Rails and a Ribbed Creation to Focus the Flow of Water directly behind the Snorkeler for Optimum Electric and Drive.