Buy two for a discount! From the manufacturer: Snap 3 Pro is Apple MagSafe compatible, adhesive assisted. It's more difficult to remove than typical MagSafe accessories because you can use other MagSafe accessories on top of it and we don't want it coming off! The magnets inside your iPhone just aren't strong enough to keep Snap 3 on your phone if you stick it to a fridge or car mount. Dimensions: Diameter - 58mm Thickness - 2.5mm