BioGuard Arctic Blue Winter Kit is a premium off-season kit. Each kit contains Arctic Blue Algae Protector, Arctic Blue Shock, and winterizing instructions. Arctic Blue Algae Protector prevents the growth of all types of algae and is approved for use with all filter types. Arctic Blue Shock will oxidize and clarify through the off-season months and it is ideal for all pool surfaces. Using the Arctic Blue Winter Kit in the off-season will make opening in the spring much easier.