Stone- Lets the user inflate the lungs by blowing into the mouthpiece. If lungs are functioning,  will release air and draw in more; repeat until calf regains consciousness. Exclusive Non-Return Valve prevents reflux and inhaling noxious mucus and gases by operator. Proper length helps prevent blowing air into calf's stomach. Developed in cooperation with the 'School of Veterinary Medicine' in Bristol, England.