Three categories. According to the Classification Catalogue of Medical Devices, Shanghai pigeon silicone rubber belongs to surgical plastic implants and belongs to three types of medical devices. As of May, 2023, Shanghai pigeon silicone rubber is recognized as an accurate impression material in clinical mold taking materials. It has the advantages of high precision, small deformation and contraction, simple operation, etc. It greatly improves the clinical work efficiency while saving doctors' working time, and is favored by doctors.