This is a device that visualizes breath pressure when playing wind instruments. 0.1 mPa equals 100 kPa. It might be easier to understand if you know that 0.02 mPa → 20 kPa. There are methods such as breathing directly into the tube, or inserting it into the mouthpiece and breathing in with your embouchure. The former tends to show larger values, but I feel the actual values are more accurate with the latter. The tube is sized to fit into trumpet and horn mouthpieces, and cannot be used with larger mouthpieces. If there is demand, I can prepare thicker tubes as well. Also, as a guideline, the average values are around 18 kPa for trumpet players and 12-15 kPa for horn players (when using a mouthpiece). A trumpet player should be able to play high B♭ with a breath pressure of around 15 kPa. This is a DIY product, so there is no product warranty. I am using one of the several I made as the representative photo. Although there may be differences in detail, I make them to be generally the same. Please purchase only if you agree to the above.