These sensors are for use with Manometers, Magnehelic® Gages, Pressure Switches and other Controllers to pick up or sense static pressure drop across air filters and cooling coils, blower input and discharge pressures, etc. The angled tips shown have 4" insertion depth. Each has four radially drilled .040" sensing holes. All except Model A-303 mount in 3/8" hole in duct. For portable use, a magnet holds No. A-303 in place. No. A-305 is used where a very low actuation or sensing point is required on a pressure switch or gage or where response time is critical. No. A-307 and A-308 are suitable for use in low velocity systems or where the need for accuracy is less critical.