smelly proof bags produced by smelly proof tm are designed to create an ecosystem that blocks vapors and oxygen from entering or exiting the nylon reinforced FDA approved poly. Made in the USA, all size bags come with a double-track zipper ensuring the tightest seal possible. smelly proof bags also have tear notches to be used with most all heat and vacuum sealers. 3 1/2 inches x 4 1/2 inches. Clear plastic.