You have no need to perform austerities, to meditate, or to practise yoga. To repeat this mantra you need no rituals or ceremonies, nor must you repeat it at an auspicious time or in a particular place." This mantra is free of all restrictions. It can be repeated by anyone, young or old, rich or poor and no matter what state a person is in, it will purify him.
https://en.wikipedia.org/wiki/Damaru
https://www.youtube.com/results?search_query=damaru
https://www.slideshare.net/search/slideshow?searchfrom=header&q=damaru
