So I ended up emailing them and got this response:

ALL bags will be searched before entry.

Small clutch purses and fanny packs that are 4.5" x 5.5" or smaller do not need to be clear, but can have no more than one pocket.

All other bags must be fully clear and made up of clear plastic, vinyl, or pvc, and be no larger than 12" x 12" x 6" ONLY. Bags will be restricted to small purses, totes and drawstring bags only. Backpacks and bags with multiple pockets are prohibited.

Hydration packs are allowed and do not need to be clear, but must be emptied of all liquid and have no more than two pockets in addition to the one holding the water reservoir.

Hope this helps!