This hood is built to UL specification. It bears NSF label which is verifiable on NSF websites. It has met the standards set by the National Sanitation Foundation (NSF), which tests public safety, health, and environment.
Option:
Upgrade to UL Listed stainless steel filter $30/pc.
Add exhaust collar (less than 4" high) of any size $50
Cut exhaust/make up air openings of any size $20