Cal. Civ. Code § 1802.6
"Retail installment contract" or "contract" means any contract for a retail installment sale between a buyer and seller, entered into or performed in this state, which provides for (a) repayment in installments, whether or not such contract contains a title retention provision, and in which the buyer agrees to pay a finance charge, or in which the buyer does not agree to pay a finance charge but the goods or services are available at a lesser price if paid for by either cash or credit card, or in which the buyer would have received any additional goods or services or any higher quality goods or services at no added cost over the total amount payable in installments if the sale had been for cash, or (b) which provides for payment in more than four installments. When taken or given in connection with a retail installment sale, the term includes but is not limited to a security agreement and a contract for the bailment or leasing of goods by which the bailee or lessee contracts to pay as compensation for their use a sum substantially equivalent to or in excess of their value and by which it is agreed that the bailee or lessee will become, or for no other or for a nominal consideration has the option of becoming, the owner of the goods upon full compliance with the terms of the contract.
Ca. Civ. Code § 1802.6