Manasara 62.24

62.24

ghanamaṣṭāṅgulasaṃyuktaṃ kuryāttatraiva yojayet
grīvasya purato bimbaṃ mūlavyāsa dvayāṅgulam

joined with a thickness of eight digits, one should fashion and attach it there. / In front of the neck is the dewlap-fold, with a base diameter of two digits;