The HKS AFR is a fuel-adjustment device that regulates the air/fuel ratio by changing the airflow voltage output to the vehicles factory computer. The AFR was designed for vehicles that are lightly tuned (intake, exhaust system, etc.) and need only slight fuel adjustment. The 12 setting adjustment indicator allows the user to enrich or lean the stock fuel settings by approximately 1.0 A/R point in either direction (richer or leaner). Type-D is designed to work on vehicles that utilize a pressure sensor.