MLTS has described the difference between the "silver" level Kryptonite u-locks and the "silver" level OnGuard u-locks: The Kryptonite "bent foot" design makes it easier and faster to use than any other "silver" level lock. The OnGuard "dual bolt" design takes a couple seconds longer to lock up, but requires that a crook cut BOTH legs of the "U", not just one.

As a practical matter, all of the "silver" rated u-locks are similar in quality. I would suggest using the smallest and lightest model that fits around both your rear wheel and a beefy parking meter post.

I use and like both the Kryptonite Evolution "mini" u-lock and the OnGuard Pitbull "Mini" TC. These are the two lightest "silver" rated u-locks that most bike shops carry.

There is a complete list of "silver" rated locks at Soldsecure. The "Magnum" locks sold in the UK are similar to the locks sold in the USA under the OnGuard brand.

www.soldsecure.com/Leisure.htm