Fully functional, original tags, very clean. Mass flow sensor for air by Books Instrument, model 5861 E Series. Includes two stainless steel Ham-Let Let-Lok  #316 3/8" compression fittings. Flow rate: 55 SLPM. Gas: Air. Process/ambient temperature: 5°C to 65°C. Base is model 586EA112E2DA. Pre-owned and tested industrial surplus from a closing plant in Quebec, Canada. Minor surface scratches only.