Ibyuma bihanitse cyane bidafite ibyuma byihuta ni uruziga rwicyuma gifungura kuruhande rumwe kandi bikozwe mubyuma 304 cyangwa 316 byo mucyiciro.Iyo ihuriro rimaze kuba, uhita usunika urutoki ahantu hejuru yugurura kugirango rukomeze. ikintu gikomeye nuko itazabora mugihe, ndetse no mubirere bitose. Nubwo mubisanzwe biza mubunini hagati ya 3.5mm na 14mm, niba hari ubunini bwihariye urimo gushaka noneho nyamuneka utubaze kuko bishoboka cyane ko dushobora kubitanga.