The insulators are made by bonding a porcelain piece with upper and lower metal fittings using an adhesive. The porcelain piece's end face, where it contacts the metal fittings, is padded with an elastic washer. The porcelain piece features structures such as sandblasting, knurling, and grooving for mechanical strength, anti-loosening, and anti-twisting. The porcelain surface is evenly coated with white glaze, and the metal fittings are painted with gray magnetic paint. The main structure of the porcelain piece comes in two types: a hollow partition (piercing-type) structure and a solid (non-piercing-type) structure. The combined bonded pillar insulators are generally of the solid non-piercing type, which reduces maintenance and testing work compared to the former structure. The porcelain pieces can have either multiple or fewer棱, with the multi-棱 shape increasing the surface distance and electrical performance over the fewer-棱 shape. All products except for the outer bonded pillar insulators that are being phased out are of the multi-棱 shape. The internal bonding structure, where the metal fittings are glued into the porcelain holes, increases the insulation distance and improves electrical performance, while also reducing the space required for installation. However, due to the negative impact on mechanical strength, insulators with high mechanical strength requirements are best suited for combined bonding (i.e., the upper fittings are internally bonded, and the lower fittings are externally bonded).