Mares Power Plana Tec FinsPower Plana Tec Fins The Power Plana is the perfect technical fin, especially for frog kicking! Made of practically indestructible natural rubber, with a negative buoyancy. The ideal fin for extended range diving. The Power Plana is the rubber fin designed by Mares aimed primarily at Extended Range diving. Rubber fin with ribs to load the water and drain channels for the same. Fin with an important weight and measure created by length of the spring.