I recently purchased a Cokin Z-Pro U960 ND Grad kit for my camera and some adapter rings, and I'm looking forward to using the filters on my camera.

Cokin Z-Pro U960 ND Grad Kit

mounted on a Canon 10-22mm lens

I wanted the Z-Pro kit primarily so I could use Neutral Density and Neutral Density Graduated filters (often referred to as "ND" and "ND Grad" filters) on my camera.

The purpose of an ND (neutral density) filter is to reduce the amount of light getting to the camera's sensor, without affecting the colour balance, contrast or colour temperature. ND filters are useful for allowing longer shutter speeds to be used (ie, for "smoothing" out water when taking photos of rivers and waterfalls). An ND Grad filter is a graduated ND filter, and has half the filter darkened, and half the filter clear. This allows you to darken a bright sky, to ensure both the sky and the subject are better exposed.