The construction of the small semi-reinforced series is made with side frames and crossbars; the large semi-reinforced series features a triangular frame and bearing support. Total airflow and pressures up to 53,800 m³/h and 1,260 Pa. They cover temperature ranges from -20 °C to 80 °C or 110 °C depending on the series.
Available in double format, with two VCTM-SR/TDA-SR fans mounted in tandem on the same shaft, with crossbar and reinforced with side frames and braces, forming a single unit. Total airflow and pressures up to 34,600 m³/h and 1,010 Pa.