Nyko Clip Grip Power for Nintendo Switch

Be careful, apparently the controllers don't lock into it. I was testing to make sure it was locked, and the controller went flying. The controller might still work. Didn't try playing it yet. Charging the Nyko grip, it has a battery in it.
You can buy it on Amazon.
Other then the controllers not locking into it, it's fine. Doesn't matter how hard you push. And you might break something if you push to hard.
Also got a Butterfox Nintendo Switch Carry-all Bag Case today. No good at making it looser. I was trying to make it longer. Might not do that.
Controller still works, the one that went flying. Must use a nice battery in the Nyko grip, it doesn't get hot. It's still charging, the controllers are done charging, but they barely lost any battery. Seeing as the grip has a battery, I probably won't need to plug it in very often.