Designed using the same interchangeable base cups as the CupFone, CupFone Duo allows for a perfectly snug fit in almost any vehicle, even with an extra phone holder. Boats, golf carts, RV’s, or any vehicle with cupholders are perfect for convenience CupFone Duo offers. An open access bottom lets you easily charge both phones in place, so no one has to worry about their phone’s charge, unless only one of you has a charger. You can also change your CupFone Duo’s plastic knobs with 11 different colors of aluminum billet knobs.