The Supra feet and clamps have an ingenious design. Once the main levers are relaxed, you adjust a small thumb wheel so that the clamps fit snugly against the roof rails. Pulling the levers back into place locks the clamps around the rails and the feet to the bars. In fact, these bars are so ridiculously easy to fit and remove, the omission of a lock is a serious security shortcoming. What's more, a maximum load rating of only 60kg is the lowest in class, which counts against the Automaxi