• Use brew water to evaluate your actual extraction in daily use.
  
• Use distilled water when calibrating or comparing readings between devices or users.

Yes! For home users, CoffeeOS will always be free.

Yes! R2 Extract has a range of 0-30% TDS, which is much higher than the concentration of espresso. For the most accurate results, you'll want to filter your espresso before measurement to avoid oils affecting your results. However, due to the CMOS sensor used in R2 being much larger than traditional refractometer sensors, results without filtering espresso will still be quite accurate.

R2 Extract takes a fundamentally different approach to measuring refractive index, using a much larger sensor that minimizes the impact of external light. This means it doesn’t require a lid and is much more durable than traditional refractometers. Unlike fragile, manual devices, R2 Extract connects via Bluetooth and syncs seamlessly with CoffeeOS, automatically calculating extraction and integrating directly with the Brew Control Chart for precise, repeatable results.