Helicopter Aircrew Breathing Device (H.A.B.D.)
... the H.A.B.D. is intended for use only as an emergency device to assist aircrew members or passengers in making an emergency egress from a submerged aircraft. Due to its limited air volume, it is not intended for use while scuba diving or egressing from depths greater than 45 ft / 13.7 m.

Before using the H.A.B.D., it is important to receive in-water survival training which simulates an emergency egress situation. you must also learn basic principals and tech- niques for breathing compressed air underwater. Use of the H.A.B.D. without proper training is dangerous and can result in serious injury or death. ...

The last time I went through water survival we had classroom instruction on the H.E.E.D.; I thought Id actually get training in the pool with one nope, classroom familiarization only. However, were I to just buy one, I would get training on its use and LIMITATIONS.