Gotta have it for snow!
I use my Contour primarily for skiing and the lens kit allows you to add ND filters to help block sunlight and keep the Contour from over exposing. The camera all by itself has a really hard time dealing with direct sun on snow, even if you properly adjust the internal settings. The ND filter (sold separately)just screws onto the lens kit when the light gets harsh and can be removed quickly if you enter shade or a low light environment. I have found that a .9 filter does a nice job and allows you to use this camera in a much broader range of light. The filter will also add as lens protection that can be easily replaced if damaged.