The Patented Insert technology allows the fin to have a straight base with no cant. Which fin makers love because of the ease in making a custom fin. Building a cant into the base of a fin, is a custom fin makers nightmare and increased cost of making a fin.
The "V" notch in the base of the fin is designed to have the crub screw land on while pulling the fin into the board creating a compression fit. The "V" notch makes it almost impossible to loose a fin after the crub screw makes contact.
After the fin is compressed into the special flex material of the Canted tappered insert by the crub screw, the fin base always pulls flush to the bottom of the board.
The downward compression fit of the fin allows for a relax fit in ProBox and not a lateral pressure fit of the older fin system designs which may fail in the board.