I have ordered Nutone CV391 vacuum bags. When I opened the package there was no brand name or any markings on the packages. I had 2 bags left and compared to the new ones, the old bags were heavier and carried the Nutone name. The new ones were much thinner, there were no clues or inscriptions on them at all. Are they actually made by Nutone? They also don't say Envirocare. ?