We can kindly confirm that our Magnetic Sticker can indeed be placed on a case and does not need to be directly on the phone. 

If you are using an iPhone that supports wireless charging but does not support the new MagSafe technology, this sticker will allow for wireless chargers such as the Satechi USB-C Magnetic Wireless Charging Cable or the Apple MagSafe Charger to magnetize onto your phone or case, in order to charge your device. 

We hope this information has been able to provide some guidance and clarification for you!