A bat includes a composite material barrel. The barrel includes a plurality of layers. A stiffening layer forms one of the exterior layers of the barrel. The stiffening layer includes unidirectional fibers, where the unidirectional fibers are oriented to substantially encircle the barrel. The stiffening...http://www.google.es/patents/US8029391?utm_source=gb-gplus-sharePatente US8029391 - Composite bat
