The popularity of GoPro has led to the development of a growing number of accessories specifically designed for that action camera, including the GoBall handle.
Duo Mount
is a mount for GoPro Hero cameras that enables users of those action cams to mount one or two cameras at the same time, creating the ability to capture two different angles at once. There are vertical and horizontal mounting holes, allowing it to be bolted in any direction, on the left or right, front or back and bottom or top. It works with all generations of GoPro Hero cameras, including the new Hero4 Session, according to its Kickstarter campaign.