This 3 stop Neutral Density filter is part of our new glass Naked Filter line which slides onto the Hero3 camera lens. This is only for filming when the Hero3 is outside the waterproof housing, or while in the "Frame" housing. This filter has a glass lens for razor sharp optics as well as maximum scratch resistance. A Neutral Density Filter or (ND Filter) is used to slow down the GoPro Camera's very high shutter speed. The ND filter essentially tricks the camera into thinking there is less light in front of it, so the camera's shutter speed is slowed down to compensate for the fake lower light levels. When the camera's shutter speed is slowed, the subjects in your video will have a slight blur motion. This means that everything that is moving in the frame will have a slight blur to it, and everything not moving, will still be in focus. To better understand, just take a quick look at the comparison video. Motorsports: An ND filter will completely transform your auto and motorcycle images and video. Usually the extremely fast GoPro shutter speed captures every little detail of the road, or the scenery, and gives the illusion that you are not moving at all. This Neutral Density filter will slow down the shutter speed and give the road and surroundings a smooth motion blur. Aviation: The GoPro is also notorious for the rolling shutter when filming from an airplane. Rolling shutter causes the aerial video to have a jello effect or wobble. The jello effect can easily be corrected with our ND filter. The ND filter will blur the prop and make smooth out your aerial videos. Quad Copter: In the last year filming with a quad copter has become very popular, Especially the DJI Phantom. The common issue with these is referred to as jello effect, caused by the Gopro's rolling shutter, high shutter speeds, and vibration. This neutral density filter is the easiest way to fix rolling shutter and smooth out your quad copter videos.