These are components and replacement parts for H-Series positive pressure headgear.
As a reference, the H-Series Hood system is described, below.

The H-Series positive pressure hoods offer superior comfort in the most demanding work environments.
They are lightweight and loose fitting with a unique airflow design which helps prevent fogging of the wide-view faceshield.
They offer higher protection than negative pressure respirators, as they don't depend on the integrity of the face seal for protection.
They also eliminate the need for fit testing or facial hair regulation.

Optional air control devices allow the supply air to be heated or cooled by as much as 50F.
With several options for headgear, faceshields and other accessories, you can build a complete powered air or supplied air system designed specifically for your needs.

Effective for paint or gelcoat spraying, sanding or general maintenance
Can be used on 3M belt-mounted powered air purifying respirators (PAPRs) as well as supplied air respirator systems
A supplied air system requires: H-Series headgear, breathing tube, air regulating valve, and an air supply hose (all sold separately).
For high pressure air supply (shop compressor; test air quality) add an air purification panel (#W-2806); for low pressure a dedicated electric air pump is required (user supplied)
A powered air system requires: headgear, breathing tube, and an appropriate PAPR and accessories