Venturi
Precise FiO2 except pts with high inspiratory flow rates
Pure O2 via fixed jet that draws in air to give known dilution
Cannot deliver humidified gas
Blue (0.24 2L/m), white (0.28, 4L/m), yellow (0.35, 8L/m), red (0.40, 12L/m), green (0.60, 15L/m)