Roadster Standard Cupholder Adapter USRS

Cupholder Adapter: Secure your bottles and cups while driving Trucks, Cars, RVs, Boats, and other Vehicles 
Expandable Base: Adjustable Size, Fits Large Mugs, Bottles, and Cups up to 3.6" with side opening for Handled Mugs
Compatibility: Compatible with Simple Modern 32oz Summit, 40oz Summit, 12oz Voyager Coffee Mug with Handle, and more!

ref USRS