From the USA Softball website (http://www.teamusa.org/usa-softball/play-usa-softball/certified-usa-softball-equipment):

USA Softball Bat Testing & Certification Program 

CERTIFIED/APPROVED: The official bat for USA Softball Championship Play must meet all the USA Softball specifications and the requirements of Rule 3, Section 1, and:

  1. The official bat, made up of the knob, handle, grip, taper, barrel and end cap shall be free of burs, dents cracks, sharp edges, rattles and show no signs of excessive wear. The official bat may be marked OFFICIAL SOFTBALL by the manufacturer, and shall be no more than 34 inches long nor exceed 38 ounces in weight. The official bat shall not be more than 2.250 inches in diameter at its largest part, including any tolerance for expansion. The official bat must bear either the ASA 2000 Certification Mark, ASA 2004 Certification Mark, or ASA 2013 Certification Mark (Slow Pitch, Men’s Adult Fast Pitch, Junior Olympic Boy’s Fast Pitch and Men’s Modified only), as shown below and must not be listed on the ASA Non-Approved Bat List with 2000 or 2004 Certification Mark.


     


AND


  1. must be included on a list of approved bat models published by the ASA


OR



  1. must, in the sole opinion and discretion of the umpire, have been manufactured prior to 2000 and if tested, would comply with USA Softball Bat Performance Standard. This includes wooden bats.


Exception: Senior Softball bats may be used in Senior Championship Play only.


    All bats in USA Softball Championship Play, except Seniors, must pass the ASA Bat Performance Standard. All bats having the 2000, 2004 or 2013(Slow Pitch, Men's Adult Fast Pitch, Junior Olympic Boy's Fast Pitch and Men's Modified Pitch ONLY) Certification Mark and not listed on the list of Non-Approved bats with Certification marks will be allowed in USA Softball Championship Play. Bats with the 2013 Certification Mark will be allowed in Slow Pitch National Championship Play Only. For your convenience, USA Softball's website has a listing of all approved bats and bats that have ASA Certification Marks and are no longer approved.


    NON-APPROVED BATS: 2004 and Beyond


    Click here for USA Softball's 1 Page Non Approved Bats with Certification Marks (2000 and 2004)
    (current listing, no changes as of January 26, 2016)

    Click here for USA Softball's Non Approved Bats with Certification Marks (2000 and 2004)
    (current listing, no changes as of January 26, 2016)

    Click here for USA Softball's Non Approved Bats with 2004 Certification Marks
    (current listing, no changes as of January 26, 2016)

    USA Softball no longer displays every bat made by bat manufacturers that do not comply with current USA Softball bat standards. If you want to know what bats are approved for use in USA Softball Championship Play, follow one of the steps below.

    • check the approved list located in the drop down boxes at http://www.teamusa.org/usa-softball/play-usa-softball/certified-usa-softball-equipment and search by the specific manufacturer or select all
    • check for either the 2000, 2004 or 2013 (Slow Pitch Only) ASA Certification Mark (all three depicted above) and then be sure the bat is not listed on the PDF's above as a Non-Approved Bats with ASA Certification Marks by USA Softball 

    Please be sure to read the specific USA Softball rules surrounding bats (a portion of which is located above) for a comprehensive review. Please remember that all bats that do not bear an ASA certification mark remain non approved unless they were made prior to 2000 and in the sole discretion of the umpire would pass ASA certification test if tested. Local USA Softball leagues and tournaments not conducted as part of USA Softball Championship Play may alter USA Softball's playing rules as they see fit.