All V-Series Supplied Air Valves require a supplied air hose to complete the NIOSH-approved respirator system. These hoses are available in many different lengths and are sold separately.
3M 37019, Versaflo Air Regulating Valve Assembly V-300/37019(AAD), 7100077491, 1 EA/Case
$224.35
Factory Stock, 7-10 Day Leadtime, Priced Per Case
Allows the worker to set the airflow to the most comfortable level. Includes the valve and waist belt. It is strictly a regulator and will not warm or cool supplied air to the worker.

3M 71878, Flexible Diamond Hand File 6210J, Yellow 18, N40, NO 1, 7000082156, 10 per case
3M 08743, Exhalation Valve 7283, 7000125987, 50 EA/Case 
