I.Okwu Mmalite Ngwaahịa:
Ngwaahịa a nwere ntọala ihe nlele na nkọwapụta nha iri dị iche iche nke efere etiti, nke dabara adaba maka (0.1 ~ 0.58) mm ọkpụrụkpụ nke ihe nlele ahụ, ngụkọta nkọwapụta 10, yana efere etiti dị iche iche, nwere ike ịgbanwe na ọkpụrụkpụ ihe nlele dị iche iche. A na-ejikarị ya eme ihe n'ọrụ mmepụta akwụkwọ, nkwakọ ngwaahịa na nlekọta mma ngwaahịa na ngalaba nyocha na ngalaba. Ọ bụ ngwa pụrụ iche maka ịnwale ike mkpakọ mgbanaka nke akwụkwọ na katọn.
U Nke 1 0.100-0.140 mm
U Nke 2 0.141-0.170 mm
U Nke 3 0.171-0.200 mm
U Nke 4 0.201-0.230 mm
U Nke 5 0.231-0.280 mm
U Nke 6 0.281-0.320 mm
U Nke 7 0.321-0.370 mm
Ọnụọgụ u nke 8 0.371-0.420 mm
U Nke 9 0.421-0.500 mm
U Nke 10 0.501-0.580 mm