California Code, Health and Safety Code - HSC § 113784

(a) The space is defined by a physical barrier from the outside environment that completely encloses all food, food-contact surfaces, and the handling of nonprepackaged food.

(b) All access openings are equipped with tight-fitting closures, or one or more alternative barriers that effectively protect the food from contamination, facilitate safe food handling, while minimizing exposure to the environment.

(c) It is constructed from materials that are nontoxic, smooth, easily cleanable, and durable and is constructed to facilitate the cleaning of the interior and exterior of the compartment.