Celtic Viking symbolism design. The design shows the "Triquetra" Viking Celtic Knot. Viking Design for Viking Lovers and Lovers of Nordic mythology. Great gift for men and women and lovers of the Celtic period, Valhalla and the time of the Vikings 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.