1. the thread workmanship, the ceramic body and the metal body connecting part of the white powder, can be wiped out by hand, powder is sealed washer stamping into the special, if it's fake, is intentionally sticky with glue, so cannot be wiped.
2. spark plug metal parts or ceramic and metal joint position has a four digit number, this is the production batch, you can call the manufacturer to inquire.
3. the licensed products have stickers on the single package of the products. The oval white sticky paper is marked on the production area, importers, enterprise standards and so on.
