First aid for patients with cardiopulmonary resuscitation and common respiratory tract asphyxia, especially for patients with difficult breath or requiring improvement of the oxygen supplement.

Body weight: ≥33kg for Adult series
10kg-33kg for Child series
≤10kg for Infant series
Capacity (Ball) 1630ml for Adult
680ml for Child
340ml for Infant
Inhalation Resistance <5cm H2O (at 50L/min)
Exhalation Resistance <5cm H2O (at 50L/min)