Each pack of 2 holders contains four pieces of 3M VHB (so you have extras), it's the best double sided adhesive I've ever used. You just press it firmly against a smooth surface, hold it for a few seconds and it snaps into place (until you're ready to remove it with a very fine scraper). The brackets themselves are also sturdy, holding the controller well without dragging it in or out, and don't have any sharp edges. I was a bit skeptical at first that two pieces of molded plastic and some glue really cost $15, but they are really very well designed and built and basically perfect for keeping controllers, headphones, etc out of the way.
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