Determining the level of security that is necessary for your particular lock-up situation is the key. Kryptonite has a new simplified security system (see below) that consists of a 1-10 point scale. Kryptonite makes security recommendations based on where you are locking and the length of time that your bike or vehicle will be unattended.
For example, a "10" provides ultimate security and is recommended in a high risk area such as a densely-populated metro area, A "1" on the other hand provides secondary security and is recommended for a low risk area such as out on the trails. To find out which lock(s) is the right one for your lock-up situation check out How to Choose A Lock.