Balanced regulator specifically designed for respirator use, the Versaflo V-500 Regulator ensures smooth airflow, optimum safety and comfort low-pressure warning whistle replaceable charcoal filter. Easy airflow adjustment. Spray gun or compressed air tool port. Approved to EN14594 with all featured headtops. Assigned Protection Factor (APF) of 40 with 3M Versaflo S-Series & M-400 Headtops, APF of 20 with all others.