USSSA Bat Standard Rules Linked Here:

http://www.usssa.com/baseball/Announcements/#/?gdSport=11&AA=512

More Information on Bats:

http://www.usssa.com/baseball/Announcements/#/?gdSport=11&AA=512

Bat Rules: Bat Rules:  14u and Younger Bats Must have USSSA 1.15 Stamp.
14u AA: can use approved -5 (or High School level bats allowed)
14u AAA teams, when playing in Open events, can use -5 approved bats. When playing in Majors or AAA listed events are required to use BBCORE
14u Majors and Higher:required to use High School approved BBCoremWood, or Wood composite