In modern use the Triquetra, also known as a "trinity knot," is believed to represent the three promises of a relationship such as to love, honour, and protect. It's an ancient symbol though and appears on runestones in Northern Europe being associated with Odin and can represent the triple goddess and protection for Wiccans and other neo-pagans.
The Triquetra also appeared on Led Zepellin's Fourth Album so whatever the symbol means to you personally this sticker will make you cool.
Your decal has a transparent layer of application tape over the top so that you can easily apply it to any clean, dry surface. The whole thing, including the clear layer is applied to the surface and when you're happy the decal is in place you just peel away the tape leaving the sticker firmly attached.
Gently peel off the backing paper. The sticker will come away from the backing paper and stay stuck on the transparent application tape. Occasionally it prefers to stay on the backing paper rather than lifting away with the tape. If this happens give the whole thing a rub over and try peeling it off again in a different direction.
Starting at one edge, carefully apply the entire sticker, transparent backing tape and all.
Give the whole thing a good, thorough rub over (a credit card works well).
When you're happy everything is stuck very gently peel off the backing tape. The sticker itself will stick to the surface and the tape will come away without leaving any residue.
Your decal is designed to last for approximately 5 years in all weathers but take care if you're a keen jet washer.
Removal: If at any point in the future you wish to remove the sticker simply heat it gently with an ordinary domestic hair dryer until it peels off. Remove any residue with a drop of ordinary lighter fluid.