LensCoat for the Canon 400 f/2. 8 with IS III LensCoat 400 III telephoto lens cover offers your valuable equipment some protection from scrapes and bumps, preserving its resale value. It also help break up the shape of your lens, making it less noticeable to wildlife. The neoprene LensCoat also acts as a thermal barrier making your lens more comfortable to handle in hot and cold tempertures. The LensCoat 400 III features a clear plastic windows over the auto focus and Image Stabilization controls, and also the distance scale. A small notch on the last segment lines up with the red dot indicator, making it easy to quickly line up your lens with camera mount even with the cover installed.