Black Zone is a new, ultra smooth co-poly. It is crafted with the latest advancements in string materials using a series of special thermal heat treatments that strengthen molecular bonding and keep the surface smooth throughout hard hitting play. It is designed for comfortable, controlled power for faster swing speeds and has excellent durability. The ultra-smooth surface makes it perfect for hybriding with synthetics. It will not bite into softer strings which can cause premature breakage. The smooth surface allows the strings to bend upon impact and then snap back into place for excellent feel, power, and spin.