Replacement Head for TSD117 Airflow Transducer - RX117 Replacement Airflow Head for the TSD127 - RX127 Replace Airflow Head for TSD137A, ±12 ml/sec - RX137A Replace Airflow Head for TSD137B, ±20 ml/sec - RX137B Replace Airflow Head for TSD137C, ±60 ml/sec - RX137C Replace Airflow Head for TSD137D, ±150 ml/sec - RX137D Replace Airflow Head for TSD137E, ±350 ml/sec - RX137E Replace Airflow Head for TSD137F, ±1200 ml/sec - RX137F Replace Airflow Head for TSD137G, ±3000 ml/sec - RX137G Replace Airflow Head for TSD137H, ±8000 ml/sec - RX137H