Little League and Cal Ripken leagues have banned the use of composite-barreled bats effective January 1, 2011. Manufacturers are able to apply for one year waivers for their composite bats, and testing is currently under way. A few bats have received waivers already and you can find a full list of approved bats here. BatWarehouse.com will prominently display which youth composite bats have received a waiver underneath the picture of the specific bat.
This does not mean that all composite youth bats are banned in all leagues. Currently, these bats are only banned in a couple of leagues. The majority of youth players can still use composite-barreled bats. Check with your league director if you are unsure of the rules governing your league.
Hybrid bats, that is bats with a composite handle and alloy barrel, ARE LEGAL for all leagues at this point in time. The ban only applies to bats with a composite barrelBPF 1.15
Youth bats are almost universally governed by the 1.15 BPF. BPF stands for Bat Performance Factor, and measures the how fast the ball comes off the bat. Bats must meet this BPF standard in order to be approved for play. Nearly all youth bats are stamped with the 1.15 BPF mark.