Pneumotach Amplifier has 2 analog outputs, one for flow and one for pressure. Dual Amplifier provides only analog flow output for each pneumotach. Consider Pneumotach Calibration which presets range control and provides chart of volts out vs. flow and pressure (volts vs. flow only on dual amp). For dual amp must buy 2 calibrations. Heater Control must be purchased separately. Dead space: 51cc Weight: 187 gram Length: 8.9cm R3830A/R4830A Ports: Both 1-1/8" OD x 0.850 ID R3830B/R4830B Ports: Large end 1-3/8" OD x 30mm ID, small end 30mm OD Fleisch equivalent: # 3 To connect pneumotach to Breathing valve with 35mm OD port use part # CC1067.