Originally Posted by ZHP_Bimmer05
are thes made for any lens? i just got the kit lens for the XTi
It depends on the diameter of the lens (should be printed on the lens). But as long as the diameter is correct it will work. These are "circular polarizers" as opposed to "linear" ones and are designed to work with AF cameras.
Also bear in mind that this filter will reduce your effective f-stop and thus certain cameras with already high f-stop lenses will have issues with AF working properly.
Originally Posted by Gamite
These slim filters don't have the external threads for additional add ons right?
Yes, that's right. They are primarily designed for wide angle lenses to prevent vignetting. However you can screw the CP onto an existing standard filter.