The Little League bat requirements have completely changed effective Jan 1, 2018.
All bats must have the USABat stamp in order to be legal.
That means all bats used in previous seasons with the "BPF 1.15" will be ILLEGAL.

The goal of this effort is to increase safety for the players. USA Baseball has concluded that recent advancements in science, engineering, technology, and the materials available to fabricate non-wood bats, now allow the manufacturers to construct youth bats that can perform at a wood-like level through the entire range of lengths and weights of youth bats.

Click the link below to get a complete list of bats that include the USABat stamp.

usabat.com