just got this email from our little league president, hope this helps:
Starting January 1, 2018 Little League National implimented a New Bat Standard. As a Chartered LL Program we are under strict Mandate to follow this new bat standard rule.
So here it is as best I can describe it. Of course you can go to this link I am providing for more detailed info, buy I wanted to sum up for you
https://www.littleleague.org/playing-rules/bat-rules/
All Bats for Little League for ages 4 thru 14 and playing in Squirts,T-Ball, Coach Pitch(Sandlot or Rookies) or any Player pitch divisions(AA, AAA, Majors, Juniors), MUST use bats that have the USA BASEBALL Logo.
These USA Baseball Bats, can come in 2 variations...Small barrel (2 1/4") or for the most part, Big Barrel (2 5/8").
In respect to all of the bats for the levels noted, there is no weight drop mandate..If the bat is stamped USA BASEBALL it is Legal. Does not have to conform to a Minus 3, Minus 5, Minus 9, etc....
In respect to Wood Bats...Provided they are a single ONE Piece Wood Bat, they are Legal and Do Not have to have the USA Baseball Logo.
Buyer beware with online companies or even sporting good stores who sometimes have a rep who does not know all the rules. Absent the USE BASEBALL Logo, the Bat CANNOT be used in Little League Baseball for Intramural or Travel.
The one Exception to this rule, is the LL aged 14 thru 16 who play in the Seniors Division, they have to use a BBCOR Bat with a -3 Drop. In Seniors, a Wood Bat can be used and does not have to conform to BBCOR standards
The Best I can do is provide you with what is Legal for Little League...As for some Tournaments, some Leagues, some private schools, I cannot address what all of them allow or don't allow. You need to check with those Leagues, Tournaments or School Coaches in respect to their requirements.
Very Important Note....In Squirts, T-Ball and Sandlot Divisions, the MCLL will be Providing to Each Team Manager, 2 USA BASEBALL approved bats for Team Use....So, if you are not sure what bat to buy or do not want to go to the expense of purchasing a bat, your Team Manager will have 2 Legal team bats for your child to use.
Hope this helps