The idea behind the Torsion Spring is to create a one piece hull where the left side talks to the right side with dynamic flex without losing kinetic energy from the wave. This core gives you the quiet, smooth, feeling of a polyurethane board. The epoxy makes it a little lighter. The Epoxy also maintains it’s flex longer, is stronger, whiter, and greener than Polystyrene and Polyurethane. Fully waterproof, if you get a small ding, you don’t have to worry about ending your session. The Carbon Kevlar tape used along the rail in this 3D perimeter reinforced construction resists buckling. The way it wraps onto the top of the tail in the fin zone frees the tail up and provides extra rebound out of turns. Biaxial cloth is used to increase compression resistance without noticeably affecting the flex.
The WPC (waterproof core) is a special developed blank that is waterproof, stronger and lighter than PU, with great flex and spring. The blank does not take in water, so if you get a ding in the water you can be back in the lineup faster than ever before.
The holes that appear in the deck of a Torsion Spring are called Thermovents. Torsion Spring/XPS blanks do crush, but not as easily as EPS or PU. When it crushes, especially in higher temperatures, it off gasses air and a small dent can turn into a small delam, which overtime, will grow. Therefore, tiny holes are put in the deck. Big enough to let the air out but too small to let water in. XPS is also very water resistant.
The "carbon kevlar" is a carbon fiber mesh in a matrix, but includes kevlar fibers to add some strength. While being light and stiff, the carbon fiber isn't particularly strong. By adding some kevlar, you sacrifice some lightness (ie, it's heavier) but gain some strength.
Because the board is stringerless, it removes the two-dimensional restriction of the board to deliver on that engineered flex. It doesn't have anything in the middle of the board, therefore, it does not divide the board by two sides. It lets one rail communicate to another rail when you are turning or when you are snapping off the lip.
Torsion Spring works great from knee high all the way to double overhead plus and exact conditions will of course vary on the board model in which the Torsion Spring is applied. TST will make you surf faster, quicker and looser with lots of drive. It will outlast your strongest board and yet it will be lightest in your quiver.