For Golf Cart - The Cup Holder has strong magnet that holds the cup holder to the railing without falling off even with the golf cart bouncing around. 80 MM (3.15") Diameter - Suitable for your drinks (cups , water bottles, cans, beers, etc) hold cups or cans up to 3.15"(80MM) diameter. Foldable and Easy to Carry - The cup drink holder is foldable when not in use. Take little space in your backpack. You can carry it without taking too much space in your bag. No Scratches - The magnets on the cup holder are covered with rubber. No scratches to the surface. Installs in seconds and rugged enough Multi-purpose - The Cup Holder allows you to keep you favorite beverage conveniently in reach. Perfect for the car, garage, workshop, office, camp site, boat, and more! The powerful magnets attract to any ferrous metal flat surface (not for curved metal surface) including toolbox, filing cabinets, grills, refrigerator, metal shelf , tractor, and heavy machinery. Not suitable for aluminum surface or stainless steel surface.