has anyone purchased the chinese Dometic duckbill valves?

[sailing_gal]

I am running low on my supply of Dometic duckbill valves for my 2 Vacuflush heads. I am currently in Spain and they are absurdly expensive to get here. However, I have found Chinese versions of these things for very good prices. They seem to have very favorable ratings from users. I was wondering if anyone here has used them, and can verify if they work properly.

[Lepke]

You can buy on Amazon.com, don't know where they're made. About 1/5 of the Amazon.co.uk price.