Many believe that saying or chanting this mantra, out loud or silently to oneself, invokes powerful benevolent attention & blessings. Viewing the written mantra is said to have the same effect & it is often carved into stones or wood & placed where people can see it. You can read more here
Spinning the written mantra in a prayer wheel is believed to have the same benefit as saying the mantra, which is why I have made the design circular. Mani wheels with copies of the mantra inside are found all over the world.
The endless or eternal knot in the centre of the design is an ancient symbol representing the interweaving of spirituality, wisdom & compassion. Since it has no beginning or no end it represents timelessness & omnipresence.
I also have a mug with the same design available which you can see here
& a bangle which you can see here