It is a handheld tool that is used to deliver positive pressure ventilation to any subject with insufficient or ineffective breaths. It consists of a self-inflating bag, one-way valve and mask. 
 
It is used for giving artificial respiration to victim of any accident in which breathing tends to stop. It is an alternative to mouth to mouth resuscitation. It has a non return, non re-breathing valve. If required, oxygen mixed with air can be also given. It is a very simple to use device.