A GLV-gas lift valve that uses dual “Fortress™” seals on both sides of the bellow 19 to protect said bellow from both high dome pressure 3 acting against outside bellow surface and high injection pressure acting against bellow 19 internal surface. When valve is in closed position, after dome pressure 3 is applied, upper-dome side “Fortress™” seal is engaged and prevents high dome pressure reaching said bellow 19 external surface. When valve is in fully open position, when injection pressure 14 is applied, lower seal 10 is engaged and prevents access of high injection pressure into bellow acting against bellow internal surface. This principle allows much higher pressures to be applied in valve dome section and injection section by reducing differential pressure across the bellow 19. In addition, lower “Fortress™” seal allows very high injection pressure 14 more than 10 KSI to be applied without damage to bellow or gas lift valve components.