Izikulufu zamahlombe ziyisici esivamile sokuxhuma komshini esivame ukusetshenziselwa ukuxhuma izingxenye futhi senza kahle ekuthwaleni umthwalo kanye nezindawo zokudlidliza. Iklanyelwe ukuhlinzeka ngobude obuqondile nama-diameters ukuze uthole ukusekelwa okuphelele nokuma kwezingxenye zokuxhuma.
Inhloko yesikulufu esinjalo ivamise ukuba yi-hexagonal noma i-cylindrical head ukuze kube lula ukuqiniswa nge-wrench noma ithuluzi le-torsion. Ngokuya ngezidingo zohlelo lokusebenza kanye nezidingo zezinto ezibonakalayo, izikulufu zamahlombe ngokuvamile zenziwe ngensimbi engagqwali, i-alloy steel, noma i-carbon steel ukuze kuqinisekiswe ukuthi zinamandla anele nokumelana nokugqwala.