Lub sijhawm tiv thaiv hluav taws ntawm qhov rooj hluav taws yog 60/90/120min. Cov qhov rooj hluav taws feem ntau muab faib ua cov qhov rooj ntoo, cov qhov rooj hluav taws steel, cov qhov rooj hluav taws kub tsis muaj steel, qhov rooj iav qhov rooj thiab qhov rooj hluav taws, txawm tias lawv yog ntoo, hlau lossis lwm yam khoom siv. Muaj peb qib A, B, thiab C.