Product review (4 stars): There is a screw adjustment made on a bellows on the initial install that required a fine tuning about a year ago
This is my second purchase of this booster, the first was six years ago. The six year old unit received lots of use over that time and required only one adjustment over that time. The unit uses a small vacuum tube the in inserted into the existing dryer vent line that monitors pressure and in turn turns on the booster. There is a screw adjustment made on a bellows on the initial install that required a fine tuning about a year ago. The unit is ver quiet when new but got noisy over the last year. Highly recommended if you have a long run for a dryer vent line(if your laundry room is in the middle of the house).