About the Transit Flex Frame Bracket - U Kit The latest innovation in U lock transportation from Kryptonite. The Transit Flex Frame Bracket - U Kit mounts quickly and easily, supporting transportation of the most common U-lock sizes. The Flex Frame fits most bicycle frame tubing whether round, oval, triangular or square shapes. 360 degree rotation on the mounting system allows for to better fit and aligns better with a bike frames specific geometry. Key Features Supports the transportation of the most common size U-locks Compatible with 13mm & 16mm round shaped shackles Fits bicycle frame tubing 25mm to 80mm (whether round, oval, triangular or square shapes) Heavy-duty Soft Strap System contours to bike frame About the Brand Over 40 years ago, Kryptonite began with a mission. While much has changed in bicycling, and bicycle security, Kryptonite\\\'s objective remains the same, they are here to empower you to protect what you value. Through constant innovation, expert guidance, and Kryptonite\\\'s never-ending commitment, they continue to pursue their passion and do everything they can to ensure you can go where you want, when you want by offering smart, serious security solutions. In 1989, an unusually high number of Anti-Theft Protection claims in central New York City, forced Kryptonite to stop offering protection there until 1994. The New York Lock was introduced in 1994 and became a flagship lock for the company. By 2013 Kryptonite became part of Allegion PLC through the spinoff of Allegion from Ingersoll-Rand. This separation allows Allegion to focus solely on commercial and residential security businesses. Bicycle Locks Buying Guide