Introducing Propel Pearl coverstock, the next extension in Brunswick coverstock technology. Propel Pearl is an evolutionary coverstock developed by Brunswick to improve the midlane and backend traction of the ball on today's slicker oils and lane surfaces. The Propel Pearl coverstock was discovered through testing of new formulation additives and process changes in coverstock manufacturing. Mechanical Asymmetric Core Engineering. The has three major benefits : Ultra Low RG core system to engage the Propel Pearl coverstock, High RG differential to aid in traction through heavy oil and High RG asymmetric differential to quicken the response time to friction. Designed as a twocomponent elliptical core system, the is dynamically the strongest asymmetric core ever produced for a Brunswick ball. The Evil Siege unites the new Propel Pearl coverstock and the proven to produce a ball motion that is strong in the midlane and aggressive on the backend. The Evil Siege is the ball when your game needs help battling medium to oily conditions and poor pin action. The Evil Siege can be drilled using the standard drilling techniques developed for asymmetric bowling balls. Please visit brunswickbowling.com/drilling_information to view the drilling instructions for specific reaction characteristics and layout details. The unique core shape of each Brunswick ball is used for weights from 14 to 16 pounds. This approach to lightweight ball engineering provides bowlers with consistent ball reaction characteristics across this weight range. The same drilling instructions can be used for 12 and 13pound balls. This is because Brunswick uses a generic core shape with an RG differential that is close enough to the 1416 pound shape.