There is a code on the network cable. The simplest way to teach you is to take out the head and tail of the network cable. If it displays 001. If the latter is in place, it should display 305. A normal network cable box is 305 meters long, not 300 meters long.

The network cable will have a string of words at certain distances, such as 030980, 030978, 030976... They are always lined up regularly. The actual numbers you see shall prevail. Due to the current shortage of manufacturers, The short measurement is normal, so we first measure one section, such as: 030980-030978, the actual length is 0.595cm, and then take the numbers of the two ends, for example, the first end of the thread is 030980, and the end of the thread is 030970, (the end of the thread is 030970, and the end of the thread is 030970) Subtract) × 0.595 {according to the actual value measured by yourself} ÷ 2 = the total length of the network cable.

For example: (030980-030970)×0.595÷2=10×0.595÷2=5.95÷2=2.975M (meters)