The shutter is a device that allows light to pass for a determined period, exposing photographic film or a photosensitive digital sensor to light in order to capture a permanent image of a scene.Our company Founder introduced the "Cat Eye/Ranger Eye" in this hook and loop format around 24 years ago and has been designing them ever since. PDW makes the best in class. “Cat Eyes/Ranger Eyes” have been in use the US military for decades. Anyone who has ever used a helmet band or patrol cap knows what these are. They can be used in pairs or individually. Our Cat Eyes are a high grade of non-toxic, durable PVC. The hook backing allows the Cat Eye to be fixed to any loop swatches found on headwear, packs, plate carriers, webgear and more.