Leaf Guard is a complete gutter system. The system includes reverse curve gutters and the downspouts. The water flows along the curve of the gutter so it does not have a screen. The components seem to be of fairly high quality.
The Leaf Guard company guarantees that the gutters will never clog. If they do the company will come out and clean them for free. They also really advertise their Good Housekeeping seal of approval. I’m not really sure about that seal. I believe the company just pays Good Housekeeping to put the seal on their site and literature so it doesn’t really mean much (except extra cost for the consumer).
For an additional review of the LeafGuard product see this Leaf Guard review.