Abstract: This invention relates to devices for preventing the spread of flame (i.e., flame barriers).The invention comprises a sheet having a backing bearing a coating of 50 to 70 weight % diorganopolysiloxane gum, 1 to 10 weight % fibrous filler, 20 to 45 weight % hollow glass microspheres, and 1 to 5 parts by weight curing agent per 100 parts by weight of said gum. The sheet (i) is substantially free from components volatilizing below 350.degree.C., and (ii) has a weight of at most 0.6 g/cm.sup.2. Preferably the coating is applied in a multilayer fashion.The present invention is a light-weight, non-intumescing sheet useful as a flame barrier between fuel tanks or engines and passenger or cargo compartments of mass transportation vehicles.