Backpack-sized bags and tote purses will have to be clear plastic, clear vinyl, clear PVC or one-gallon clear zip-top bags.
Small clutch bags and fanny packs between 4 to 5 inches wide do not have to be made of clear plastic.
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Non-plastic hydration packs with a capacity of 2.5 liters that have no more than two pockets will also be allowed.
"We are taking every step to ensure Outside Lands is a secure and positive experience for all festival patrons," Allen Scott, concert head for Another Planet Entertainment said in a statement.
Many festivals have adopted the clear bag policy because it reduces time for security checks and enhances safety, according to Scott.