Insulators are composed of ceramic components and top and bottom metal fittings bonded together with adhesive. The ceramic component ends are in contact with the metal fittings through elastic pads, and the bonding sections of the ceramic components are structured with sanding, knurling, and grooving for mechanical strength, anti-loosening, and anti-torsion. The ceramic surfaces are uniformly glazed white, while the metal fittings are coated with gray magnetic paint. The main structures of the ceramic components of the insulators consist of two types: hollow partition (penetrable) and solid (non-penetrable) structures. The bonded支柱 insulators are typically of the solid non-penetrable structure, which reduces maintenance and testing workload compared to the former. The ceramic components of the insulators come in two shapes: polygonal and non-polygonal. The polygonal shape increases the surface distance, offering better electrical properties than the non-polygonal shape, with the exception of the gradually being phased out external bonded支柱 insulators, all other products are polygonal. The internal bonding structure, with metal fittings inserted into the ceramic component holes, increases the insulation distance and improves electrical properties, while also reducing the space occupied during installation. However, due to the adverse effect of internal bonding on mechanical strength, insulators requiring higher mechanical strength should be bonded jointly (i.e., the upper accessories use internal bonding, and the lower accessories use external bonding).