The only problem with the amazon part is you won't have a rubber seal, that would need to be added into the fitting to create the water seal @ the isolation valve, otherwise it would need to be PTFE tape.
If you're prime then normally there's free returns.
I'm not Prime, can return but might have to pay for postage, not worth the hassle it's just a fiver. I'll just keep it and add a rubber seal (I have a few), and if that doesn't work then I can fall back on the rad valve extender option.
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