FIT System - The FIT system eliminates measuring, cutting and trim for a perfect fit every time 2 ., 58 dBA (3.0 sones) at Low Speed - Keep noise down in the kitchen with the quiet operation of 68 dBA (6.4 sones) 3 at the hood's highest speed with a recirculation option., Hidden Vent, Powerful Variable-Speed, 225 CFM Motor Class 4 - Variable speeds provide the right amount of ventilation for every meal you prepare. 4 Based on a vertical 7" round duct installation. Performance varies based on installation., Incandescent Lighting - Incandescent lighting makes it easy to see what you're cooking with bulbs that are inexpensive to replace.