1. Response time responsetime is the time required when the indication value of the detection device rises to 90% of the target concentration. 2. Indication error error is the difference between the indication value of the detection device and the value measured by the standard method. 3. Repeatability: The ability of a detection device to provide similar indications under the same measurement conditions, expressed as relative standard deviation. 4. Anti-interference selectivity refers to the change in the output value of the detection device after being exposed to a certain concentration of interference gas. 5. Test mode testmode Products with formaldehyde concentration digital display function (such as air purifiers, fresh air fans, air conditioners, etc.) only provide a mode for detecting formaldehyde concentration and do not provide other functions.