Universal Heavy-Duty Cup Holder Mounting Pedestal by Arkon®. This heavy-duty car cup holder mounting pedestal features a 25mm (1 inch) ball head and is compatible with Arkon or other third-party 25mm device holder, including those from RAM Mount. It fits easily into car or truck cup holders and the one-piece base twists to expand to fit cup holders up to 3.5 inches in diameter.