What' your favorite Duct Fan Speed Adjuster? I thought about getting this one, but I read a few bad reviews: Amazon.com: Duct Fan Speed Adjuster: Home & Kitchen
You will be good with this one, i have one its nice and simple just plug your fan into it and you can adjust the speed with the dial.
This is the type I use: SE Electronic Stepless Speed Controller - Amazon.com Has a switch to turn on full...or use dial setting...or turn off