The quantity of zinc oxide will make adifference in the SPF factor. You need not contact the company. As per US laws, any company that claims sun screening effects, must mention the SPF factor clealr and must be approved by the FDA. otherwise, it is not reliable. Thy are not supposed to sellthat in the USA and this can be brought to the notice of FDA. If this company is sure about its product, it should get FDA approval. I wonder why they are not doing that.