Camo Neoprene Cover.
Lenscoat part number TC400DOFG.
The forest green TravelCoat for the Canon 400mm f/4.0 DO IS AF Lens from LensCoat is a 3.0mm-thick, shock-absorbing, closed-cell neoprene lens cover. It was designed to fully protect the lens when it is not in use, without the need for a more comprehensive lens case. It allows more valuable room in your camera bag for other necessities. The coat slides over the lens, and closes with a secure touch fastener. This classic forest green camouflage pattern is useful for when you are shooting in wooded areas.