What is the difference between this and a trimmed impeller

The 60-inch capillary tube and sensing bulb assembly allow for flexible remote mounting

If your local code or application requires thermal protection

Superior Material Durability: Engineered to resist wear

BROAN-NuTone S97017607 Grille/Spring Assy 321042-401 What is the difference betweenThe Broan NuTone S97017607 Grille Spring Assembly is a high specification OEM replacement part engineered to maintain the structural integrity and airflow efficiency of your bathroom exhaust fan. This genuine Broan NuTone part includes the ventilation fan cover and the necessary replacement grille springs required for a tight, flush mount against the ceiling. Frequent vibration and moisture exposure in ventilation systems can lead to fatigued springs