Film VK-25 is a phenol-rubber film adhesive made from an alcohol solution of phenol-formaldehyde varnish FL-511, varnish GR-S, and a rubber mixture solution based on synthetic and natural rubber in solvent (product 4). Film VK-25A is a phenol-rubber film adhesive made from an alcohol solution of phenol-formaldehyde varnish FL-5111, varnish GR-S, and a rubber mixture solution based on synthetic rubber in solvent (product 4A).