Metcal hct 900 hot air convection tool metcal hct 900 21 the metcal hct 900 hand held convection tool provides a low cost versatile rework solution for a wide range of production and rework applications it has a compact robust design with analogue controls for both airflow and temperature a closed loop feedback circuit maintains the temperature at the desired level regardless of changes in the airflow volume metcal hct 900 21 hct 900 hot air convection tool