California Code, Public Contract Code - PCC § 10129

(a) Notwithstanding Section 3400, no agency of the state charged with the letting of contracts for the construction, alteration, or repair of public works may draft or cause to be drafted specifications for bids, in connection with the construction, alteration, or repair of public works, (1) in a manner that limits the bidding, directly or indirectly, to any one specific concern, or (2) calling for a designated material, product, thing, or service by specific brand or trade name unless the specification is followed by the words “or equal” so that bidders may furnish any equal material, product, thing, or service. In applying this section, the awarding authority shall, if aware of an equal product manufactured in this state, name that product in the specification.Specifications shall provide a period of time prior to or after, or prior to and after, the award of the contract for submission of data substantiating a request for a substitution of “an equal” item. If no time period is specified, data may be submitted any time within 35 days after the award of the contract.

(b) Subdivision (a) is not applicable if the awarding authority, or its designee, makes a finding that is described in the invitation for bids or request for proposals that a particular material, product, thing, or service is designated by specific brand or trade name for any of the following purposes: