Feem ntau, cov menyuam kov muaj ob hom: EU style thiab US style.Eu style muaj ib tug pas nrig, yog haum rau cov teb chaws Europe thiab Australia ua lag luam mas, qee lub teb chaws kuj siv nws.Asmeskas style muaj ob hom tawb, 4 tawb thiab 5 tawb.Nws yog nrov nyob rau hauv teb chaws USA, Canada thiab lwm yam North America cheeb tsam, South America cheeb tsam thiab hais txog.
Cov pas nrig muaj ob txoj kev kho mob, Zinc plated thiab Chrome plated.Chrome plated zoo dua, Zinc plated yog kev lag luam.Qws muaj ob txoj kab uas hla, 5.7 hli thiab 7.7 hli.7.7 mm muaj zog dua, tab sis 5.7 mm loj yog txaus rau ib txwm tej yaam num.
