Bolarƙirar mai nau'in 7 wani nau'in ƙulli ne wanda aka yi amfani da shi a wurin ginin, tare da siffar mai siffa 7. Haka kuma ana kiransa ƙarfafa anga farantin anga kusar, welded anga aron kusa, anga kambori anga aron kusa, jijiyar farantin karfe anga aron kusa, anga aron kusa, anga dunƙule, anga waya, da dai sauransu An musamman binne a kankare tushe da kuma amfani da matsayin tushe ga kayyade daban-daban inji da kayan aiki. Maballin anga mai siffa 7 yana daya daga cikin kusoshin anga da aka fi amfani da su. Kwallan Q235 gaba daya ana amfani da shi ne wajen kera abubuwa, kuma ana amfani da kayan Q345B ko 16Mn don aiki tare da karfi mai karfi, sannan kuma ana amfani da kayan 40Cr don sarrafa kayayyakin da karfin 8.8, kuma ana amfani da karfe na sakandare ko na uku a wasu lokuta. An rarraba kusoshin anga zuwa ulu, sanduna masu kauri da sanduna na sihiri a cikin nau'i daban-daban. Ulu, ma’ana, karafan abu, ana sarrafa shi kai tsaye daga karafa ko waya ba tare da sake tsari ba. Itace sanda mai kauri kuma ana kiranta da suna A, ita kuma siririn sandar ana kuma kiranta da B, dukkansu ana yinsu ne da karafa bayan an canza su izuwa diamita sanda ake bukata. Welded anhor bolts ana yin su ta hanyar walda farantin ƙarfe mai taurin kai tare da madaurin kai ɗaya. Juriyarsa na ja da ƙarfi. Dangane da yanayi daban-daban na amfani, zasu iya kaiwa 3.6, 4.8, 6.8, 8.8, da dai sauransu Thearfin ƙarfin ƙarfin ƙarfin ƙarfin ƙarfe na 3.6 mai fasali mai nauyin 7 shine ƙarfin ƙarfin ƙarfe kanta. Tenarfin ƙarfin ƙarfin anga da aka sarrafa kai tsaye tare da Q345B ko 16Mn albarkatun ƙasa za su iya kai ƙarfin ƙarfin ƙarfin maki 5.8.