Damaru (Damru) is a small drum with two sides separated from each other by a thin neck-like structure symbolizes the two utterly dissimilar states of existence, unmanifest and manifest. Damru is a drum,which is always seen in the hands of Shiva,while doing the Tandava. The damaru is also used by musicians, due to its small portable size. When a damaru is vibrated, it produces dissimilar sounds which are fused together by resonance to create one sound. The sound thus produced symbolizes Nada, the cosmic sound of AUM, which can be heard during deep meditation. According to Hindu scriptures, Nada is the source of creation.
Shiva is adored as the Damru Paani, as well.
This Damru is made up of Brass , its small in size ( around 6 cms) with a single chord , but i found the sound much better than larger Damru's. The grip is also very good.
Reference of Damaru in ancient texts :-
nṛ tāvasāne naṭarāja rāja nanāda ḍakkāṁ navapaṁcavāram|
uddhartu kāmassanakādi siddhān etad vimarṣe śiva sūtra jālam||
नृत्तावसाने नटराजराजो ननाद ढक्कांनवपञ्चवारम्।
At the cessation/culmination of His Cosmic Dance,
Shiva---- the Lord of Eternal Dance,
with a view to bless the sages Sanaka and others,
played with His "Damaru" fourteen times,
thus vibrating fourteen Sutras,
for the universal Vimarsha/deliberation purposes
in the cosmic net of the Shiva Sutras.
The above shloka is a prologue of the Maheshwara Sutra,also revered as the Shiva Sutra,where DAMRU beats are of the highest significance. Creating the vibrations,originating from the source OM, is the essence of all the Sanatana Dharma Shastras. Om is itself the very Shabda Sharira/sound body of Shiva.The scriptures say:The 'Naada" is the creation of Lord Shiva as the Nataraja. During his cosmic dance,he created the 'Nine beats',while lifting the one leg and then 'Five beats' ,lifting the other leg for maintaining the the universal pulsation in harmony.Nine and five is equal to fourteen, and these happen to be the 14 Sutras of the Vedic literature .