FreshAir Hood Ventilation - Hood Oberon's NEW Lightweight Hood Ventilation System - Hood Mount configuration - may be added ONLY to Oberon ArcFlash Hoods purchased since February 2007 that include black loops on inside back surface of hood shell. Add steady stream of external air into the hood for comfort. Conveniently battery operated. Requires 4 "AA" batteries (either Alkaline (lasts over 2 hours of use) or Rechargeable (lasts about 1.5 hours of use). Not for Respiratory protection. Not a NIOSH approved system. This is just the ventilation unit, does not include the hood. Hood purchased separately.