Gosen AK Pro Spin 15L is a medium firm synthetic gut with good control and decent pop. It has a textured outer wrap for added bite. Featuring Gosen's Umishima construction, this string uses a composite microfiber technology combined with special nylon and co-polymer (3) island process. According to Gosen, this increases the dynamic elasticity to provide controllable power and less shock. We found this string to have a comfortably firm feel with good pocketing and decent durability for a non-poly. Directional control is excellent in this thicker gauge. A great option for the non-poly player seeking a nice compromise between precision and power. The high level of control permits high swing speeds, which is perfect for adding spin.