Circular Polarizing Filters are like sunglasses for your camera. You know how when you put your glasses on, the world looks warmer and the blues of the sky look more saturated? That's what these filters do. They also reduce reflections (if you want to photograph water or through windows). I was dubious if I was spending money and would even notice the difference, but I was shocked at how obvious it was. These come with hefty carrying cases that ensure they're scratch-free in my bag, but it's probably going to be living on my camera most days! Really great quality, and beautiful photos as a result.