In July 2023, in order to meet the requirements of higher precision and high-quality products, Hitto Seiko developed JOISTUD-S to reduce warpage and burrs, while providing greater anti-rotation strength. They conducted research using manufacturing and mold manufacturing technology, and developed JOISTUDHT with high anti-rotation strength, JOISTUD-SS with space-saving function, JOISTUD-WP with waterproof function and high-strength JOISTUD-S. JOISTUD-WP is a product with waterproof function. Like JOISTUD-S, JOISTUD-HT can be simply press-fitted to the fastening elements, achieving higher product quality than ever before and providing strong support for the production and operation of customers. Generally, traditional bolts use uniform and thick leaf-shaped anti-rotation protrusions, while JOISTUD series of anti-rotation protrusions only leave a ring-shaped design on the edge of the leaf. The anti-rotation protrusion is also designed to prevent lifting of the fastener. In addition, the groove inside the anti-rotation protrusion can accommodate the fastener deformed at the time of press-fitting, prevent the deformed portion from protruding in the screw direction and forming a burr, and improve the anti-rotation strength in the rotation direction.