If you are one of the thousands of homeowners who installed Broan (NuTone) bathroom fans when your home was built, this provides an easy replacement should your fan fail. I had no holes to drill or modifications to make, just unscrew a sheet metal screw - and the pre-drilled hole in the new engine block matched the existing hole perfectly. The reason I only gave it four stars is because this unit sounds even louder than the original. Some people may prefer loud noises to mask other noises from the bathroom, personally I would prefer a quieter fan but I don't want to spend a lot more money and make changes to my ceiling and/or airflow for a quieter unit. .