Reliability is measured by the Mean Time Between Failure (MTBF). High-quality aftermarket Flygt seals should offer a service life comparable to OEM parts, typically exceeding 8,000 to 10,000 operational hours in standard wastewater conditions. Look for features like leakage-proof testing at the factory and pressure resistance ratings that match the specific Flygt pump series (e.g., 3000, 5000, or 7000 series). A warranty period of at least 12 months is a strong indicator of supplier confidence in product durability.