The Sentinel D‑Box Twin Fan 250mm (Stock Ref: SENT250T) is a high-performance commercial demand ventilation unit. Designed for duct sizes from 100mm to 500mm, it delivers airflow between 0.001 and 1.3 m³/s and operates at pressures up to 650 Pa. Fitted with energy-efficient EC/DC motors and a lockable isolator, this fan ensures safe and efficient operation. Its durable Aluzinc construction is suitable for both internal and external installation. Manufactured under BS EN ISO 9001 standards and tested to BS848 Part 1 & 2, the Sentinel D‑Box Twin provides reliable, energy-conscious ventilation for a variety of commercial applications.