Our Accessories Model DP-1A Explosion Proof Pressure Switch Class 1, Div. 1, Groups C & D Class II, Div 1. Groups F & G Model DP-1B Explosion Proof & Flame Proof Pressure Switch 24 VDC Class 1, Div. 1, Groups B, C & D Class II, Div. I, Groups F & G Model DP-1C Explosion Proof & Flame Proof Pressure Switch 120 VAC Class I, Div. I, Groups B, C & D Class II, Div. I, Groups F & G Model AV-1BG Enclosure Vent Enclosure Volumes up to 15 Cubic Ft. Model AV-2BG Enclosure Vent Enclosure Volumes from 15 Cubic Ft. to 300 Cubic Ft. Model F-1 Air Line Filter