Subow bipipe-ka birta waa qaybo muhiim u ah nidaamka tuubbada si loo beddelo jihada qulqulka dareeraha. Waxaa loo isticmaalaa in lagu xiro laba tuubooyin oo leh isku daro ama kala-baxsanno kala duwan oo caan ah, iyo in tuubadaha loo rogo jihada qaarkood 45 darajo ama 90 darajo.
