The second sound means measuring achieved. Please remove power meter immediately, do not stay for a long time. The third sound means system power off automatically.If after a long warning tone, the display shows "888.8", it means that the machine is breakdown. If the display shows "000.0", it means the temperature of the surface is too high or it is out of the measuring range. You can use the machine again after the temperature down. Return must in original package and not been used. The item "CO2 Laser Tube Handheld Power Meter 0-200W for Laser Engraving Cutting Machine" is in sale since Friday, August 12, 2016. This item is in the category "Business & Industrial\Healthcare, Lab & Dental\Other Healthcare, Lab & Dental". The seller is "cnsigntech" and is located in ShangHai. This item can be shipped worldwide.