Tee Ball - Bats must have the USABaseball certification and the words "Only for use with approved Tee Balls", or be wood.

Baseball (Rookies & Minors) - Bats must have the USABaseball certification, or be wood.

Baseball (Intermediate & Juniors) - Bats must have the USABaseball or BBCOR certification, or be wood.

Baseball (Seniors) - Bats must have the BBCOR certification, or be wood.

Softball (Rookies-Majors) - Must state "Softball" on the barrel and have a BPF of 1.20, or be wood.

Informational Links:
Little League Bat Information
Little League Baseball Bats Standards
Little League Baseball & Softball Bat Rules
Little League USA Baseball Bat Standard FAQs
USA Baseball Approved Bat List