. . . aluminum. They are carbon fiber as are virtually all the leading brands (Easton, Demarini). Temperature does impact the flex in these bats. In fact, you can make an argument that below 40 degrees you're better off using aluminum alloy as those bats are impacted less by temperature. That said, whatever they use yesterday seemed to have plenty of 'flex'. I wouldn't change a thing. If a bat of two gets damaged you replace them. ** Edited by MidloHokie at 3/28/2026, 8:03:23 AM