Cal. Veh. Code § 16452

An operator’s policy of motor vehicle liability insurance shall insure the person named as insured therein against loss from the liability imposed on that person by law for damages arising out of use by that person of any motor vehicle not owned by that person, and for any subsequently acquired motor vehicle for a period not to exceed 10 days from date of purchase, within the same territorial limits and subject to the same limits of liability as are provided for in an owner’s policy of liability insurance.