Hidden defects warranty. Under Articles 1641 to 1643 of the Civil Code, the seller is required to guarantee the product against hidden defects that make the product unfit for the use for which they are intended, or that decrease this use as far as that the beneficiary would not have acquired the good or would have paid a lower price if he had known the hidden defect. In case of a dispute regarding a hidden defect, the beneficiary must act promptly in accordance with Article 1648 of the Civil Code and will have the choice between the full refund of the price of the product affected by a hidden defect, or keep the good in exchange of a partial refund. The Association is not required to guarantee the product against apparent defects which the beneficiary could have or should have noticed at the time of purchase. Similarly, the Association is required to guarantee the product against hidden defects that were known at the time of the sale, and that it refrained from notifying the beneficiary. Only the bill, voucher or receipt are admissible as a warranty certificate for the beneficiary vis-à-vis the Association.