With a straight 78mm opening, this lock is suitable for fat tires . Lock is NR (Non Key Retaining when lock is open). 8.5 mm steel shackle The case, the shackle as well as supporting elements of the locking mechanism are made of special hardened steel Closing mechanism for easy attachment of accessory to the lock body Extra large aperture (enlarged to standard version 5650) ABUS automatic cylinder Two keys are supplied with the lock The NR (non key retaining) version allows taking the key out of the cylinder