When procuring parts for compressed air dryers, you must prioritize compatibility and pressure ratings. Key specifications include the Maximum Operating Pressure (typically 10-16 bar for standard industrial use), Filtration Precision (measured in microns, e.g., 0.01μm for high-purity needs), and Thread Standards (NPT vs. BSPP/BSPT) to ensure leak-free integration. For desiccant dryers, verify the crush strength and surface area of activated alumina or molecular sieves to ensure optimal dew point performance.