The Mistral Wall Exhaust Fan 8" with model number EF8001/MEF8208 is highly efficient. It has a built-in oil receptacle and is equipped with back flow louvers to prevent foul air from flowing back inside. It also has a built-in thermal fuse for safety.The Mistral Wall Exhaust Fan 8" is a highly efficient. It has a built-in oil receptacle and is equipped with back flow louvers to prevent foul air from flowing back inside.