First prototype sold individually. Hand-shaped by Master Force Fin designer Bob Evans, placed four on a pair of Rip Force Fins. Their spin out to the side when kicked led to the epiphany that created the Water Tracking Devices, including Whiskers on the Extra Line of Force Fin. Extra Line of Force Fins includes Extra Force Fin, Excellerating Force Fin, Adjustable Force Fin, Rip Force Fin and Multi-Force Fins. Whiskers and other water tracking devices are not at this time in production. In clearing some boxes from storage, we found a box of these original prototypes.
Sold as each, as a collectible. Not recommended for use on fin or for kicking. These prototypes are without geared surfaces as was added to final product sold. The prototypes will spin to the side when kicked against, then pull in, responding to water flow. The final product controls the water flow.