Compatible with Various Bicycles: These bottom bracket screws are designed for use with a wide range of bicycles, including electric bikes. They are compatible with crank arms and chainrings, ensuring a secure connection for smooth pedaling. Durable Steel Construction: Made from sturdy steel, these screws are engineered for long-lasting performance. They offer high strength and resistance to wear and tear, ensuring they stay firmly in place even after extended use. Easy Installation and Removal: The screws are designed for easy installation and removal using an 8mm hex wrench. Their precise dimensions allow for quick and efficient maintenance without the need for specialized tools. Prevents Loosening: Featuring a special locking design, these screws help prevent loosening over time. This is particularly important for high-performance bicycles and electric bikes, where secure crank arm attachment is critical for safe and efficient riding. Ideal Size and Design: With a screw size of 21.7mm x 21.5mm, a stud length of 13.4mm, and a bottom outer diameter of 15mm, these screws fit standard and electric bicycle crank arms, providing a reliable solution for fixing your chainrings or crank arms securely.