Kirschbaum Spiky Shark is the latest update to Super Smash Spiky, using an octagonal (8-sided) profile to bite the ball for added topspin and slice. Surprisingly easy on the arm, while maintaining tension and durability.
This 8-sided string has produced improved spin, control and pace on my serve. Have had good success serving at the 4.0-4.5 levels. Also, it has eliminated elbow pain that I've experienced from stiffer spin-oriented strings.