The DarkSonic is specifically designed to assist with horizontal yoyo play. It features the “double V” bump area like the [H5] to reduce string friction with the body of the yoyo when it is turned horizontal. C3yoyo design member Ron Chan about the DarkSonic: We first design (h5) in 2010 summer. The shape of (h5) look common but in 64.5mm diameter, this really need to work with the large surface area when playing in horizontal. So we developed “Double V” bump area try to reduce the contact area between String and Yoyo. In 2011, I wanna have a better performance in 5A horizontal. I can tell 5A horizontal is pretty different from what we saw in 1A. This is the origin of DarkSonic. DarkSonic make an evolution from (h5) “Double V” bump area. Long spin and designed for horizontal tricks.