Cal. Revenue and Taxation Code § 6366.4

(a) There are exempted from the taxes imposed by this part the gross receipts from the sale of, and the storage, use, or other consumption in this state of, tangible personal property purchased by a nonprofit museum regularly open to the public that is operated by or for a local or state government entity, or operated by a nonprofit organization which has qualified for exemption pursuant to Section 23701d, provided the property is purchased and used exclusively for display purposes within the museum. (b) The exemption provided by this section extends only to items that have value as museum pieces and does not extend to display cases, shelving, lamps, lighting fixtures, or other items of tangible personal property utilized in the operation of a museum. However, the exemption does include sprung instant structures used as temporary exhibit housing. (c) For purposes of this section, a “museum” includes only any of the following: (1) A museum that has a significant portion of its space open to the public without charge. (2) A museum open to the public without charge for not less than six hours during any month the museum is open to the public. (3) A museum that is open to a segment of the student or adult population without charge. (d) This section applies only to the San Diego Air & Space Museum and the California Science Center.