The insulators are made by gluing a porcelain piece with upper and lower metal attachments using adhesive. The porcelain piece end faces are lined with elastic pads where they contact the metal attachments. The gluing areas of the porcelain pieces feature structures such as sandblasting, knurling, and grooving, providing mechanical strength, anti-loosening, and anti-twisting properties. The porcelain surfaces are uniformly glazed with white enamel, while the metal attachments are coated with gray magnetic paint. The main structure of the porcelain insulator can be either a hollow partition (penetrable) or solid (non-penetrable) design. The combined adhesive-mounted column insulators are generally solid and non-penetrable. This latter structure reduces maintenance and testing work compared to the former. The main structure of the porcelain insulator can also be either a hollow partition (penetrable) or solid (non-penetrable) design. The combined adhesive-mounted column insulators are usually solid and non-penetrable. The porcelain insulators come in two shapes: with or without multiple edges. The multi-edge shape increases the surface distance and has better electrical properties than the single-edge shape. All products except for the gradually being phased out external adhesive-mounted column insulators are multi-edged. The internal adhesive structure, where the metal attachments are glued into the porcelain holes, increases the insulation distance and improves electrical performance, also reducing the space occupied during installation. However, due to the negative impact on mechanical strength, insulators requiring high mechanical strength should use a combined adhesive mounting (i.e., upper attachments with internal gluing and lower attachments with external gluing).