Astanga Hrudaya
पूर्णेऽब्देऽङ्गुलमादाय तदर्द्धार्द्धप्रवर्द्धितम्। त्र्यङ्गुलं परमं छिद्रं मूलेऽग्रे वहते तु यत्॥१३॥
At its tip, the orifice should allow free movement of soaked Mudga (green gram), Masha (black gram), Kalaya (round pea) and seed of Karkandhu Jujube respectively.
english translation
pUrNe'bde'GgulamAdAya tadarddhArddhapravarddhitam। tryaGgulaM paramaM chidraM mUle'gre vahate tu yat॥13॥
hk transliteration by Sanscript