IMPORTANT RULE CHANGE FOR BASEBALL DIVISIONS FOR THE 2018 SEASON.  Softball, Tee Ball, and Senior Baseball bat rules did not change.
Do not buy a baseball bat for 2018 until you read this information. 
Please note: This is just a summary of relevant changes.  See links below for complete rules.

All non-wood bats used in 2017 will be prohibited for the Rookie, Minor, Major, Intermediate, and Junior Baseball divisions in 2018.
Little League Baseball (and many other youth leagues) have adopted the USA Baseball bat standards for 2018. 
Unless the bat is made from a single piece of wood, it must contain the USA Baseball Logo stamped or screened by the manufacturer directly onto the bat. 
See image below for samples of the required logo.  Be aware that some retailers are using a USA Baseball sticker, which contains the logo, that it intended for Tee Ball bats only and affixing it to the outside of unapproved bats.  This sticker cannot be a substitute for the logo being stamped or screen printed directly onto the bat, unless the bat is only used for tee ball.
See links on this page for answers to frequently asked questions USA Bat Standard or for more details about the new bat rules. 
If you have any questions please email the league's Equipment Manager or Chief Umpire.