I wasn't expecting too much on the quality side based on the price but to be fair they are just as good (if not identical) to the RS product.
Good solid construction - sealed from one side to the other through the connector, but would recommend an o-ring around the flange if using outdoors or in more humid conditions.
Low contact resistance, I can't measure a loss in SWR with the instruments I have. No noticeable degradation in signal strength when used as a feed-through from outside to inside the shack.
Overall a great product for the price.