The insulators are composed of porcelain components and upper and lower metal fittings bonded together with an adhesive. The contact areas between the porcelain ends and the metal fittings are padded with elastic washers. The bonding sections of the porcelain components feature structures such as sandblasting, embossing, and grooving for mechanical strength, anti-loosening, and anti-torsion properties. The porcelain surface is uniformly coated with white glaze, and the metal fittings are painted with gray magnetic paint. The main structure of the porcelain components in the insulators consists of two types: hollow partition (penetrable) and solid (non-penetrable). The combined bonded pillar insulators are generally solid and non-penetrable. This latter structure reduces the maintenance and testing workload compared to the former. The porcelain components have two shapes: multi-angled and less-angled. The multi-angled shape increases the surface distance and has better electrical properties than the less-angled shape. All products except the gradually phased-out external bonded pillar insulators are multi-angled. The internal bonding structure, due to the metal fittings being glued into the porcelain holes, increases the insulation distance and improves electrical performance, while also reducing the space required for installation. However, as internal bonding is not favorable for enhancing mechanical strength, insulators with higher mechanical strength requirements should use combined bonding (i.e., the upper attachments use internal bonding, and the lower attachments use external bonding).