Effective on January 1, 2018, Little League Baseball® complied with the new USABat standard. No bats previously approved for use in Little League play (Junior League Baseball and below) is permitted to be used in any Little League game or practice, or other Little League function, event, or activity. As of January 1, 2018, USABat Standard bats must be used in the Little League Major Baseball Division and below. Either USABat Standard bats or BBCOR bats must be used at the Intermediate (50/70) Baseball and Junior League Baseball Divisions. At the Senior League Baseball Division, all bats must meet the BBCOR standard. For more information on the USABat standard and a complete list of bats approved through the USABat Standard, visit usabat.com. To view bats that have been decertified for use by USA Baseball, visit usabat.com/decertified-bats.
Also, please visit the FAQ on Little Leagues website found here and here.