Product review (4 stars): At least 3 cups full of lint. Easy to use. Don't pay for this service, do it yourself.
After reading several articles about cleaning your vent pipes to avoid fire hazards, mildew smell and dryer efficiency, we decided to purchase 2 kits because the pipe runs up the wall into the attic before it exits the roof so we figured 24 ft should be enough since I can't see how many turns it makes in the wall. Do follow the instructions, we did use a drill and every few feet or so we would pull the line back down so we could pull out the lint.  The instructions made it sound like drill 1 ft at a time and keep attaching rods, the problem is if there is a lot then in my opinion you could wedge a chunk somewhere and then it is stuck, so we preferred to pull it back down and clear the lint every so many feet. Suffice it to say we must have collected over 3 cups worth. Yuck...But I was so excited to do some laundry to test it out. The dryer seemed to make the clothes slightly more fluffy and slightly better smelling but I will need to do a load of towels to really see how much of a difference it makes in drying time and overall scent improvement. I always clear out my lint trap on the dryer after every load, so that also helped. At the same time we decided to run a sanitize cycle in our washer as well. We did wait for the price to drop to $16 each but it did fall as a low as 14.90...so set up camelcamelcamel.com and monitor it for a price drop.