Posted by a reviewer on Amazon

The cards have a slight reflective sheen to them as to make them waterproof that does alter the precision but if you are not using this for professional photography it shouldnt be a big issue

Posted by a reviewer on Amazon

I recently bought a color cheker passport and the surface of it is really matte so either way its oriented it will not directly reflect light and will give you a correct white balance

Posted by a reviewer on Amazon

Didnt quite understand the use of other card