A waje diamita na zafi-birgima sumul bututu ne kullum fi 32mm, da bango kauri ne 2.5-200mm. A waje diamita na sanyi-birgima sumul karfe bututu iya isa 6mm, da bango kauri iya isa 0.25mm. Diamita na waje na bututu mai bango na iya kaiwa 5mm kuma kaurin bangon bai wuce 0.25mm ba.

Kullum amfani da sumul karfe bututu ne Ya sanya daga 10, 20, 30, 35, 45 da sauran high quality-carbon bonded karfe 16Mn, 5MnV da sauran low gami tsarin karfe ko 40Cr, 30CrMnSi, 45Mn2, 40MnB da sauran sanyi bonded karfe 16 m ko 40Cr. Ana amfani da bututu mafi yawa don bututun ruwa.45, 40Cr da sauran matsakaicin ƙarfe na carbon da aka yi da bututun da ba su da kyau don kera sassan injiniyoyi, irin su motoci, tarakta sun jaddada sassa na gabaɗaya don tabbatar da ƙarfin da gwajin ƙwanƙwasa. Ana isar da bututun ƙarfe mai zafi a cikin yanayin zafi mai birgima ko yanayin zafi mai sanyi.