Rec-mounts Double Contour Handlebar Mount for Contour Roam Roam2 (31.8mm) for contour ROAM ROAM2 Adapter up and down 1/4Tripod There's a hole CNC Machined 6061 T6 Aluminum Max 31.8mm facebook https://www.facebook.com/recmounts cycle catarog(PDF) http://www.an-y.com/img/rec-mount-catalog3.pdf