What material is the most advanced hook in the mine?

The hooks used in the mine are the most advanced I know at present: the materials of Shanghai 1 and Zaozhuang 1 are all plastic hooks with invention patents! ! ! Because the iron hook was used in the mine before, the material cost was high, the installation was inconvenient and it was easy to be corroded. So there should be a big market for new plastic hooks! ! ! Worth popularizing! ! ! My friend is from the mine! ! ! I just called him to ask. ..