Feature 1Aluminum Alloy Material: Made of premium aluminum alloy, the mid motor crank arm is built to last, offering excellent durability and strong support for electric bikes. 2Compact and Lightweight Design: With a compact and lightweight design, the mid motor crank arm exerts minimal pressure on electric bikes, ensuring a stable and efficient riding experience. 3ISIS Splined Hole with 10 Teeth: Equipped with an ISIS splined hole with 10 teeth and an inner diameter of approximately 18mm/0.7in, the mid motor crank arm offers a secure and reliable connection. 4Compatibility: Specifically designed for mid motors, the crank arm set is perfectly suited for BOSCH electric bikes, allowing for optimal performance and compatibility. 5Convenient Installation and Disassembly: The mid motor crank arm is designed for easy installation and disassembly, providing practicality for users, making it convenient to use.Item Type: Crank ArmMaterial: Aluminum alloyWeight: Approx. 555g/19.6ozCenter Distance: Approx. 170mm/6.7inSpecifications: ISIS spline hole (10 teeth, raised point inner diameter about 18mm/0.7in) .wang-edit-text{ font-family:'Arial' !important; } .wang-edit-text table { border-top: 1px solid #000; border-left: 1px solid #000; } .wang-edit-text table td, .wang-edit-text table th { border-bottom: 1px solid #000; border-right: 1px solid #000; padding: 3px 5px; } .wang-edit-text table th { text-align: center; }Package List2 x Crank Arm