http://www.gslsoftball.com/gsl-rules/
Section 4 – Equipment
GSL recognizes only USSSA and/or NSA licensed/approved softball bats.
The official softball used in championship play will be a GSL stamped,
Apex 50/375 Core softball (size according to program played).
GSL reserves the right to make changes or withdraw any approval or disapproval of any equipment at any time should in GSL’s determination change the game, effect the safety of participants or spectators, or creates a player’s performance to be more a product of the equipment rather than their individual skill.