Gun Collector Item design. 357Mag Spent Bullet casing Brass- Awesome Gun collector gift This is perfect for the avid Gun collector- these are depicting used or spent brass of popular gun calibers Adhesive backing attaches the PopGrip to your case or device. Will not stick to silicone, leather, waterproof, or highly textured cases. Works best with smooth, hard, plastic cases. Not compatible with wireless charging Printed top is swappable with other compatible PopGrip models. Just press flat, turn 90 degrees until you hear a click and remove to swap.