Mares Plana Avanti X3 FinsPlana Avanti X3 Open Heel Fins A great open heel fin with 3 channels for maximum thrust! CHANNEL THRUST Soft longitudinal inserts allow a controlled deformation of the fin blade while kicking. This channel shape moves a greater amount of water resulting in more thrust for the same effort. Features: ABS PLUS BUCKLE FOR ONE HAND ADJUSTMENT 3 CHANNELS FOR MAXIMUM THRUST STABILIZING TRIM TABS MID SIZE BLADE WITH DURABLE CONSTRUCTION