Features: 100 percent new and high quality Features: No need to power on, you can quickly distinguish the material grades of nickel steel according to the redness time In winter, the temperature is too low. Before testing, use a lighter to heat the surface for 3-6 seconds. Put a drop of this identification on the steel surface, observe the time when the color turns red, and confirm the steel grade (model). The faster it turns red, the worse the material! 200 (ordinary 201): red within 5 seconds, and red within 30 seconds is 200,200 materials are also good or bad manganese exceeds the standard 201 (Authentic 201): turns red in about 50 seconds manganese exceeds the standard 202: red in about 1 minute manganese exceeds standard 301: Red in 2-3 minutes, the color is very pale, please look carefully new national standard food grade steel 304: It doesn't change red within 3 minutes, at most the bottom color becomes darker old national standard food grade (older is better !!!) Capacity: 12ml package includes: 1pcs x steel testing fluid