The Kryptonite u-lock was developed by Stanley Kaplan, in 1972 Michael Zane bought the lock and company from Kaplan. In the early 1970s, in the US, the only proven method to secure one's bicycle was by the use of case hardened security chains with hexagonal links, but some cyclists were making the mistake of using inexpensive chains or cables that could be breached by thieves using commonly available tools. Indeed, local hardware stores would often sell inexpensive chain cut to length using simple bolt cutters. The first Kryptonite lock model was made of sheet metal cut and bent to shape, but the company soon went to the now universal circular cross section.