I have used this in toilet waste line (macerating electric toilet) as one way valve which can easily be opened for winter storage. Does not block or leak there (my experience is two summers). I bought now another set for the new boat.
Have been looking for such a type of check valve longer. The valve is very easy to handle and the maintenance is child's play, the part is perfect. In comparison to the competitors, the price and quality is unbeatable.
Due to the different connection diameters, the valve can be mounted well. So far I could test the check valve only in trial operation, it works very well.
The idea is great. You press the gray ring and the valve can be cleaned. However, you have to push hard and pull at the right moment. Disassembling and assembling is a pain. Much worse If the valve is tilted slightly, it is not tight. I fumbled for many hours to install the check valve without stress. And even then it was leaking. A lot of water ran out of the rubber seal, even though there was zero pressure on the hose. Conclusion It's crappy to open and at the same time it's never tight. bad design.
In the past, SVB was known for fast deliveries. Times seem over now. Ordered on Monday, the check valve in stock was not there on Friday. Therefore, it went back then again. Sorry SVB, you were better! Schol. SVB: Even if it has not quite a lot to do with a product evaluation: The delivery was delivered to the neighbor by the DHL parcel service on Fri, 25.05.12 15:57.