This mount is for a GoPro Session and you can adjust the angle from about 15deg to 45deg. It mounts with zip ties or a strap. There are also zip slots on the back inner wall so you can zip tie around the adjustable flap to secure it in place even more if you desire.
Here is the instructional video :
ATTENTION: The initial use of the adjustable track will be very tight. This is normal. As you adjust it a few times it will loosen up. If you see a strand or two of filament coming off the edge of the dovetail track please remove it with pliers to free up the tracks to make it move freely.