My brother-in-law brought me a charger just smaller than this for my Samsung note20 ultra recently when I was in the hospital. My phone had drained, and it “charged” overnight. The phone wouldn’t even turn on.
If I hadn’t just got the dual-port model above, I might have been in for a few of these GaN models. (But I still might…)
Just a friendly heads up to any possible buyers.
I’ve just opened one of the two items I ordered, and they don’t come with the USB C cable.
I’ve briefly scanned the product listing and it doesn’t say that it’s only the plug part of the equation, but I feel like most people might expect the cable to be in there.
I already have a Samsung USB C plug with no cable at home, so rather than return the 2 Otterbox plugs, I’m gonna roll the dice on the 3 Pack of Samsung USB C cables, and hope they work with these plugs. 
This is the way they’re sold now. Charger is charger, cable is cable. Try Anker, Cable Matters, Baseus, ESR for good quality cables. (The Baseus recoiling one is a pip.)
FWIW, I’ve been very happy with the Otterbox chargers I’ve bought. They support Samsung’s fast charging. At least, all the ones I’ve bought here do.