Our die-cast aluminum forestry fittings (Instantaneous) have identical halves and all sizes have the same head size. They are designed for low pressure forestry fire service where a quick connection must be made (1/4 turn). The die-cast aluminum ends are not designed for higher pressure washdown or in applications where there will be excessive tugging and twisting. For more rigorous environments we now offer high-visibility glass-filled nylon/poly adapters that are fully interchangeable with standard aluminum forestry adapters but are more durable, light in weight, and will never corrode or seize.