A PA rating is obtained via a Japanese testing protocol to measure the protection against UVA rays (the aging rays). In the U.S., as per FDA regulation, sunscreens simply state if they offer protection from UVA rays (via a Broad Spectrum claim) but it doesn't indicate exactly what level of UVA protection that is. Until recently, PA +++ was the highest UVA protection rating but an update to the protocol now allows for PA ++++. Any Supergoop! products that have a PA rating will be visible on the packaging next to the SPF number.
PA +++ products: Superscreen Daily Moisturizer, Unseen Sunscreen, Sun-Defying Sunscreen Oil with Meadowfoam, City Sunscreen Serum, Daily Correct CC Cream (Fair/light-Medium), Zincscreen 100% Mineral Lotion
PA ++++ products: Everyday Sunscreen
Learn more over at the Bright Side