Just read this today in the guidelines section on AHA homepage:
1. What kind of bottle is required?
Beer, mead and cider entries must be in bottles that hold a minimum of 10 ounces in volume, and that will fit in a standard case box slot. The measurements of a standard case box slot are 2.75 inches long x 2.75 inches wide x 9 inches high (7 cm x 7 cm x 22.9 cm). Bottles may be of any color and must be free of ink, paint, or paper labeling other than competition entry label. Obliterate any lettering or graphics on the cap with a permanent black marker.
Bottles with Grölsch-type swing tops and 22 oz Bomber bottles are not allowed.
Corked bottles and odd-shaped bottles are acceptable as long as they can fit in a standard case box slot (2.75 inches L x 2.75 in W x 9 in H; 7 cm x 7 cm x 22.9 cm). Bottles with raised lettering are acceptable if they fit in a standard case box slot.
Bottles not meeting the above requirements will be disqualified.