Vertical Mounting Cup Holder: Cup holder mounts into super strong magnet with 2 screws, which will securely hold your beverage in place. Super Strong Magnet: Once stick on ferrious metal, will not move anymore. Suitable for any flat ferrious metal surface like bus, mower, tractor, truck, treadmill, toolbox, grill, etc. But can't work on stainless steel surface because they are not magnetic. Anti-Drop Design: Cup holder surrounded with more wires, makes it protect small size drinks from falling. Anti-Rust/Anti-Scratch: Drink holder is made of sturdy carbon steel material with thick electroplated finish, magnet is coverd with rubber, will not rust, can work for years. Also the cup holder will not scratch the surface of appliance. Fit Different Bottles: The cup holder measures 3.3 inches in diameter, and 3.6 inches in height, fits for most cups, cans, cans with sleeves, bottles, tumblers, etc.