A bat, which has a hollow barrel and an internal assembly configured to resist deformation of the hollow barrel, is disclosed. The internal assembly includes multiple rods disposed longitudinally within the hollow barrel. The internal assembly can include a deformable ring having a substantially circular outer wall having a diameter less than an inner diameter of the hollow barrel and multiple holes, with each hole configured to at least partially receive a rod of the multiple rods. The bat can have an end cap including end cap holes extending partially through the end cap, with each end cap hole configured to at least partially receive a rod.