Will Work On All Types Of Metals and Most Fiberglass Five Piece Kit Re-Usable For Multiple Projects Bill Hirsch has been supplying sealer worldwide since 1965. Kit seal holes and seams better than any other sealer. It has greater strength and at the same time has the flexibility that a product of this type is required to have something other sealer do not have. It is a non porous coating and is not affected by alcohol, ethanol, or fuel additives. It will work on all types of metal and most fiberglass tanks where as some other sealers will not work on all metals or fiberglass tanks.