Check valve good.. Adapter bad.
So I just got around to installing this check valve. The check valve did its job and it held 43psi just fine. The only problem is, I had a slow seeping leak from the adapter that goes from 10 female to 8 male. I proceeded to swap out the 8an female mating hose end because I had a bunch of new ones sitting in a box and the leak continued. I tightened it up more and it continued. So now I am ordering a new adapter piece off Amazon. 10 bucks and I hope it solves the problem..