The new Quantum Classic Black has been designed with 3.5 times more coverstock increasing durability and performance longevity with an amazing pin impact you not only see but hear! Why does more coverstock improve the pin action so much? More coverstock enhances the Coefficient of Restitution which is the ratio of the differences in velocity between two objects before and after a collision. The higher the restitution, the faster the pins will move after being struck by the ball, transferring that increased kinetic energy to the surrounding pins producing greater pin action! The combination of our Relativity Flip solid reactive coverstock with our high-density, redesigned Quantum Mushroom core, provides effortless skid through the front, maintaining axis rotation for the strongest backend reaction of any Quantum’s to date on medium oil lane conditions.