Excellent for freediving, scuba diving and experienced users The Quattro Power Fins are a staple among instructors and divemasters because of their excellent power to effort ratio. Quattro or four refers to the "Channel Technology" design for efficiency. Water "channels off the fin blade not unlike a river overflowing its banks and cutting channels for the water to flow easier over itself". Soft rubber, anatomic foot-pocket worn without boots or over a bootsock. Oversized blade. Four channel thrust system allows for more power than longer fins. Blade stabilizers improve stability and eliminate ankle-twisting. Rubber side rails improve elasticity, and maximize resistance to cuts and abrasion. Features: Anatomical foot pocket Rubberized side ribs 4 channels for greater thrusting power Long blade, ideal for both scuba and apnea