Please ensure that the case is MagSafe-compatible or the magnetic attachment won't occur
Assembly instructions
Stack the two stickers together
One side should be magnetically stronger than the other
Verify which side of the MagSafe stickers magnetically attaches to the phone the strongest
The weaker side goes into the cavity of the grip
Insert the sticker into the cavity and press down so that the adhesive of the sticker adheres to the bottom of the cavity
If the adhesion is weak, you can glue or tape the sticker down
Mount the phone to the magnet and you're all set!
Additional notes
Take caution when using this grip lying down
The magnetic attachment is strong (and strongest when the sticker is strongly adhered) but like any MagSafe accessory, extreme shaking will knock the phone off
I've tested the phone to stay attached even with mild shaking