I actually needed some 45° feet to angle my Dolby Atmos speakers into my room and couldn't find any anywhere until I came across these. I've now bought two pairs and they work spectacularly for the Sonos Arc. If you're sitting further than about six feet from it, you need to adjust the angle so that the height channel fires into the room.
If you randomly come across this review, these are great for other things besides their original purpose.