*** hd-safe drive ** Characteristics: 1. As this product uses mems gas sensor and is equipped with re-calibration function, accuracy is very high. 2. Its cute and quality looking design gives pride and convenience to carry. 3. It uses LED display and 5 colored lights to display measured value. Green color: Represents 0.00% Yellow color:0.01~0.02% Orange color:0.03~0.04% Light red color:0.05~0.10% Thick red: Represents values over 0.10% Specification: 1. Power source:1 AAA size battery 2. Sensor type: Mems gas sensor 3. Display format: Leddisplay(5 colors) 4. External dimansion:57 x 34 x 13mm 5. Weight: About 20g (including dry cell ) 6. Temperature in use:0\'\'c - 35\'\'c 7. Storage temperature:0\'\'c - 70\'\'c 8. Power consumption:151ma How to use: Before using this product, please make sure that you do re-calibration. How to re-calibrate: 1. When pressing down the small button and staying for approximately 3 seconds, the 1st re-calibration starts. 2. After lights quickly travels right and left, green colored light turns on to the most left side. 3. When green colored light is on, blow into the inhaler for approximately 3~5 seconds. 4. When the above 1st re-calibration is finished,2nd re-calibration continues. While lights travels right and left, wait for approximately 7 seconds to have green colored light on 5. When green colored light is on, blow into the inhaler for 3~5 seconds as same as the procedure in the 1st re-calibration. 6. Power turns off automatically. We are looking for dealer, distributor, importer to represent our products in your state or city. If you are interested in getting sample and entering into business with this product feel free to contact us without hesitation.