Shrinkfast 998 Heat Gun UL Guard Protection Basket This is an imperial Guard Protection Basket. A metric Guard Protection Basket is also available and can be found here. The Guard Protection Basket (Part# 43A on the diagram) is used to guide the user to an appropriate distance for heat application. By preventing the Combustor (part #30) from being to close or coming into contact with a surface or body part, the UL Guard Protection Basket is an important safety measure for any and all uses.