CRUSHPROOF CRU-ACT400DYNO, 4 x 11' Dynamometer Exhaust Hose, Heavy-Duty, Grey The CRUSHPROOF CRU-ACT400DYNO is a heavy-duty dynamometer exhaust hose engineered to safely and effectively remove harmful exhaust fumes during vehicle testing. This 4 diameter, 11' long hose is constructed from a high-temperature EPDM rubber blend, ensuring durability and reliable performance in demanding shop environments. Designed for use with fan-assisted systems, the CRU-ACT400DYNO maintains its shape under pressure, preventing kinks and blockages that can compromise ventilation.