When evaluating spacers, prioritize anti-static materials (such as specialized polymers or stainless steel) to ensure the medication does not stick to the walls, maximizing the Fine Particle Fraction (FPF) delivered to the lungs. Ensure the device features a one-way high-efficiency valve with low inspiratory resistance, which is critical for pediatric or elderly patients with low lung capacity. Additionally, verify that the universal backpiece is compatible with all standard Metered Dose Inhalers (MDIs).