The table below lists the Noctua A series fans and their stated performances, at 12 Volts, with a Low noise Adapter or with an Ultra Low Noise Adapter. Noctua lists their airflow specs in cubic meters per hour. The table below restates these in the traditional cubic feet per minute (CFM). In the right column are listed the various Low Noise Adapters (L.N.A.) and Ultra Low Noise Adapters (U.L.N.A.). Noctua provides these in various versions. The single-digit NA-RC model numbers are PWM Low Noise Adapters. Double-digit NA-RC model numbers are three-wire Low and Ultra Low Noise Adapters. The RPM signal is always present in these adapters, and operates even when the ULNA adapter is used.