Made largely from rubber, a stiff plastic sheet, one-third lighter than aluminum, can be used in place of that metal in self-sealing, bulletproof fuel tanks for military planes, tanks and scout cars. The new product has been announced by Goodyear Tire and Rubber company, which calls its material Plioform. The United States Rubber company announces a product with somewhat similar properties which is designated simply as Formula C-102. The fibrous substance developed by Goodyear has qualities surpassing aluminum as a shell for the fuel tank in resisting leakage when hit by bullets. If machine gun bullets “tumble” while passing through aluminum they tear the metal in a way that often holds open the punctures made in the inner selfsealing lining. The nonmetallic material is less vulnerable because it does not flare under gun fire, gives maximum support to the lining and will not bursf if the plane crashes.