Product review (4 stars): Effective!!
This product is as claimed, effective in stopping the reverse flow of air back into the dryer duct. By forcing the air to be capped on top of the exit tube, it relies on a greater gravity to rest and cap the tube, rather than the standard hinged flap, which can clog in an semi-open position.

I haven't had this in operation long enough to withness the extent of lint that is trapped in this product, but it easily accessable for cleaning.

The one dentriment is that the plastic must be painted to prevent staining and breakdown of the plastic body, by excessing sunlight. Kind of pain. Hopefully future versions will be issued in sufficient white coloring so as to prevent sun exposure damage.