Kukho iintlobo ezininzi zezikrufu ezidityanisiweyo, kubandakanywa izikrufu ezibini ezidityanisiweyo kunye nezikrufu ezithathu ezidityanisiweyo (iwasha eflethi kunye newasha yasentwasahlobo okanye iwasha eflethi ehlukileyo kunye newasha yasentwasahlobo) ngokohlobo lwezixhobo ezidibeneyo; Ngokohlobo lwentloko, lunokwahlulwa lube yi-pan yentloko ye-screws, i-countersunk head combination screws, i-hexagonal combination screws yangaphandle, njl. Ngokwezinto eziphathekayo, ihlukaniswe ibe yi-carbon steel, insimbi engenasici kunye ne-alloy steel (iBanga le-12.9).