To reduce the risk of dropping the Polarizer it's usually safest to attach it off the camera. Slot one clip from the Polariser into the slot on the front of the holder.
Snap the clip on the other side into place.
Your Polarizer will be held securely in place, and the Holder can be attached to the Adaptor Ring. Any other filters can then slide into the Holder in the normal way.
With LEE100 Polarizer at 16mm (Photo Mark Bauer)
As well as increasing the contrast between sky and cloud the Landscape Polarizer has a warm bias that enhances the greens, browns and golds of landscape scenes.
A polarizer will reduce your exposure up to 1⅔ stops.