Little League has strict guidelines regarding what bats are permitted for use.

Softball is pretty easy. All softball bats must be no more than 33 inches in length for majors, minors, and farm, 34 inches for Junior/Senior League.  All softball bats cannot be more than two and one-quarter (2¼) inches in diameter, and if wood, not less than fifteen-sixteenth (15/16) inches in diameter (7/8 inch for bats less than 30 inches) at its smallest part. Non-wood bats shall be printed with a BPF (bat performance factor) of 1.20.  Note- 1.15 is not 1.20.  1.25 is not 1.20.  It can only have a printed BPF of 1.20. 

Wooden bats must be one piece (cannot be 2 or more put together) and since they must be one piece, bamboo is not allowed. Bamboo bats, by definition, are many pieces of bamboo put together.  Bamboo is not wood, it is a grass.

For Tee-Ball and Baseball, 

The bat must be a baseball bat which meets the USA Baseball Bat standard (USABat) as adopted by Little League. It shall be a smooth, rounded stick, and made of wood or of material and color tested and proved acceptable to the USA Baseball Bat standard (USABat).  USABat –  The bat diameter shall not exceed 2⅝ inches for these divisions of play.  Wooden bats must be one piece (cannot be 2 or more put together) and since they must be one piece, bamboo is not allowed. Bamboo bats, by definition, are many pieces of bamboo put together.  Bamboo is not wood, it is a grass.  It shall not be more than 33 inches in length, and 2 5/8 in diameter. 

In short- All non-wood bats must either be stamped with the USABat logo- USA Baseball’s Youth Bat Performance Standard.  USSSA is not USA, and USSSA (also known as "U-Trip" are not legal),

Confused?  Below is an illustration of the various bat stamps- note there is only one permitted in Little League Baseball play.

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