Brand new, unused, and unopened. AET SH-3511S 4P, 4 spike insulators. These are high-end products from the SH series. Recommended for those seeking authenticity. Thorough High Strength and Low Center of Gravity Audio insulators require high strength. If the strength is insufficient, the power and sound localization will not be stable, and you will not be able to experience the true essence. The SH series uses a combination of high-strength aluminum alloy and industrial carbon steel for extremely high strength specifications. And for the spikes, while maintaining strength, the height is about 1/3 that of the conventional model, resulting in a lower center of gravity and even higher sound quality. Carefully Selected and Examined High-Quality Materials The high-rigidity aluminum alloy used for the body is a custom-made product from a domestic material manufacturer. It has the same weight as aluminum but the same strength as steel, extremely fast vibration propagation, and less howling, making it a wonderful material. Contact Points That Achieve Further Strength The contact points of the spikes and bases, which are subject to very large stresses, are made by cutting "S45C" carbon steel, a Japanese industrial grade material, from round bars and applying a special heat treatment. The strength is dramatically improved by heat treatment, contributing to the power and other aspects. Hardness Surface Treatment Contact points are closely related to vibration treatment. "HV700" is applied to the carbon steel at the contact points for thorough hardening treatment. The dramatically higher hardness compared to conventional surface treatments contributes to improved edge and speed. Further Evolved Irrational Number Application Design It is no exaggeration to say that the sound quality of an insulator is determined by "strength." The irrational number application design that achieves strength has been further evolved and reborn into a new design with even higher strength. Product Name: SH-3511S Materials: High-rigidity aluminum alloy, S45C carbon steel Surface Treatment: Special hardening treatment (high-rigidity aluminum alloy), HV700 (S45C carbon steel) Dimensions: Diameter 35mm, Height 17mm (protrusion 6mm)