Kryptonite created the Series 2 bicycle locks, after more than 40 years leading the antitheft locks sector. A new and innovative range of locks that are the perfect combination of portability, comfort and maximum protection for your bike.The Kryptonite Kryptolok Combo, U-lock is composed of a 13mm thick cylinder. The open and closing system is a four-digit combination lock, no keys are needed. The manufacturer gives it a security rating 6 of 10, indicated for areas of moderate theft.MORE INFORMATION: How to choose the best lock to protect your bike?